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HANDBOOK 
 
 OF 
 
 PLANT DISSECTION 
 
 BY 
 J. C. ARTHUR, M.Sc., 
 
 Botanist to the New York Agricultural Experiment-Station, 
 
 CHARLES R. BARNES, M.A., 
 
 Professor of Botany in Purdue University, 
 AND 
 
 JOHN M. COULTER, PH.D., 
 
 Professor of Botany in Wabash College \ 
 
 EDITORS OF THE 
 BOTANICAL GAZETTE. 
 
 NEW YORK 
 
 HENRY HOLT AND COMPANY 
 
 1886 
 
 I iRR ARY 
 
COPYRIGHT, 1886, 
 
 BY 
 HENRY HOLT & CO. 
 
 Press of W. L. Mershon & Co. 
 Rahway, N . J, 
 
PREFACE. 
 
 A rich harvest of laboratory manuals has resulted to 
 zoology from the publication of Huxley and Martin's Ele- 
 mentary Biology ten years ago. Although that work 
 embraced both animals and plants with over half the 
 examples from the latter, it has given rise to no similar aid 
 to botanical study till the past year. The increasing 
 laboratory facilities in this country seem to warrant the 
 expectation that an elementary manual like the present 
 work will now be found in many instances to afford wel- 
 come assistance to both teacher and pupil. 
 
 In 1882 one of the authors of this book drew up an out- 
 line of work for a few plants, which was used in the Summer 
 School of Science of the University of Minnesota. Not 
 long afterward the preparation of the present hand-book 
 was actively undertaken by the three authors conjointly, 
 and has since been gradually perfected and tested by 
 repeated use with classes and individual students. 
 
 Although the present work is based upon Huxley and 
 Martin's in form and mode of treatment for the laboratory 
 part, it differs in excluding all matters of physiology so far 
 as possible, as the present demands of vegetable physiology 
 will hardly permit harmonious treatment along with a course 
 of dissection. 
 
 In drawing up the outlines of work the aim has been to 
 direct the student in a very careful and systematic exam- 
 ination of a few examples, so that while he is securing a 
 knowledge of the main features of plant anatomy, he will 
 
iV PREFACE. 
 
 at the same time acquire the habit of close and critical 
 observation, which is indispensable to the successful pros- 
 ecution of natural history studies. To this end the direc- 
 tions for finding the different parts have been made as 
 explicit as possible, and at the same time as little informa- 
 tion given about them as seemed 7 advisable ; for the 
 student having found the part is expected to examine it 
 thoroughly until he has found out all that may be readily 
 seen. This rule has been modified according to the diffi- 
 culties to be overcome, and in extreme cases full information 
 has been provided, which the student is only expected to 
 verify. On the other hand, it will repeatedly happen that 
 more may be learned by an acute observer than there 
 is any hint of in the outlines, as the work, though 
 deemed sufficiently exhaustive for the student, is far from 
 being so for the specialist. 
 
 In the use of such outlines as these there is always 
 danger that the student will slight the study of those parts 
 which he is expected to work out for himself and only 
 attempt to verify the portions where the information is 
 fuller. If it be found that too great dependence is being 
 placed on the manual it will be advisable to substitute 
 plants allied to those named, thus withdrawing all exact 
 information ; the laboratory directions will still serve as a 
 guide to the order and methods of examination. 
 
 It has been no part of the present aim to provide a key 
 to the nomenclature of plant anatomy. When tech- 
 nical terms are used, as indeed is necessarily very frequent, 
 they have usually been preceded by descriptive definitions, 
 either direct or implied. A glossary is added to further 
 assist the student, so that he may find as little difficulty with 
 the names as possible, and devote himself chiefly to the 
 objects themselves. On this account, and on account of the 
 progressive series of forms which have been chosen, it is 
 
PREFACE. V 
 
 hoped that the work will be found suitable not only for 
 classes pursuing a regular course of lectures, but also for 
 those who have never before studied botany, and for 
 home use away from the assistance of a teacher. 
 
 The required apparatus, reagents and materials have been 
 reduced to a minimum, difficult manipulations (except the 
 cutting of sufficiently thin sections) have, to a large extent, 
 been excluded, and the minute anatomy has been kept 
 within the limits of the average microscope used in the 
 botanical laboratories of this country, in short, the attempt 
 has been to provide a guide to the study of a few common 
 plants in which simple appliances, coupled with persever- 
 ance and keen observation on the part of the learner, are 
 the only essentials. 
 
 Under "gross anatomy " the plant is first examined with 
 the aid only of a hand lens, and then passing to " minute 
 anatomy," every part is subjected to the compound micro- 
 scope. A student's success in the latter may often be 
 gauged by his ability to discover all there is to be seen 
 under the former. 
 
 The laboratory work for each plant is preceded by direc- 
 tions for the preliminary finding and preparation of mate- 
 rial. It is followed by annotations which serve a number 
 of purposes : (i) to explain obscure matters, (2) to give 
 additional information which for want of higher powers, 
 special reagents or proper materials, the student is unable 
 in the usual limited time to secure for himself, but which is 
 essential to fully round out the subject, more especially, 
 however, (3) to give some insight into the course of develop- 
 ment from the lower to the higher forms which will serve as 
 a thread on which the most important facts ascertained in 
 the laboratory work may be strung, and not the least (4) 
 to direct the student to sources of additional information by 
 means of which he may pursue his inquiries as far as he 
 
vi PREFACE. 
 
 may choose. The annotations are necessarily fragmentary 
 and disconnected, and the references to literature only 
 sufficient to start the student in his researches. 
 January, 1886. THE AUTHORS. 
 
CONTENTS. 
 
 ILLUSTRATIONS IN GROSS ANATOMY. 
 
 Explanation of Plate I, * 
 
 ILLUSTRATIONS IN MINUTE ANATOMY. 
 
 Explanation of Plate II, xiii 
 
 INTRODUCTION. 
 
 Instruments, - I 
 
 Reagents, - 4 
 
 Care and use of microscope and lens, 6 
 Section cutting, - 
 
 Mounting, - - u 
 Applying reagents, - - ! 3 
 
 Care and use of material. - 15 
 Drawing, - - - 16 
 
 Books of reference, - 19 
 
 GREEN SLIME (Protococcusviridis}. 
 
 Preliminary, - 22 
 
 Laboratory work, 23 
 
 Annotations, - - 25 
 
 DARK GREEN SCUM (Oscillaria tenuis). 
 
 Preliminary, - - 28 
 
 Laboratory work, - - 29 
 
 Annotations, - 3 1 
 
 COMMON POND SCUM (Spirogyra quinina). 
 
 Preliminary, - 3 2 
 Laboratory work, - 34 
 
 Annotations, * * 39 
 
vm CONTENTS. 
 
 WHITE RUST (Cyst opus candidus). 
 
 Preliminary, ^ r 
 
 Laboratory work, - . - - 44 
 
 Annotations, _ _ - 48 
 
 LILAC MILDEW (Microsphara Friesit). 
 
 Preliminary, - - - 52 
 
 Laboratory work, . _ - 52 
 
 Annotations, - - - l 55 
 
 COMMON LIVERWORT (Marchantia polymorpha). 
 
 Preliminary, _ _ - c8 
 
 Laboratory work, _ . ^ 
 
 Annotations, - . - 77 
 
 MOSS (Atrt'chum undulatuni). 
 
 Preliminary, - - - 84 
 
 Laboratory work, _ - 86 
 
 Annotations, - yj 
 
 MAIDEN-HAIR FERN Adiantum pedatum). 
 
 Preliminary, - Io ^ 
 
 Laboratory work, . Io ^ 
 
 Annotations, - - 124 
 
 SCOTCH PINE (Pinus sylvestrts). 
 
 Preliminary, _ - 130 
 
 Laboratory work, - - 132 
 
 Annotations, - - - - - 161 
 
 FIELD OATS (Avena sativa). 
 
 Preliminary, - ij 2 
 
 Laboratory work, ^ J72 
 
 Annotations, - 2 
 
CONTENTS. ix 
 
 TRILLIUM {Trillium recurvatum). 
 
 Preliminary, - 197 
 
 Laboratory work, 198 
 
 Annotations, - 215 
 
 SHEPHERD'S PURSE (Capsella Bursa-pastoris). 
 
 Preliminary, - 222 
 
 Laboratory work, - 223 
 
 Annotations, - 236 
 
 GLOSSARY, - - 243 
 
 INDEX, - - 251 
 
X * 
 
 EXPLANATION OF PLATE I. 
 
 ILLUSTRATIONS IN GROSS ANATOMY. 
 
 Fig. i. Diagram of an open flower of Trillium showing the 
 number and relative position of the parts : s sepals, p petals, st 
 stamens in two whorls, c carpels each bearing two ovules. Drawn 
 with pen. 
 
 Fig. 2. Diagrammatic drawing of Marchantia to show the mode 
 of branching, somewhat enlarged. As one branch of each new 
 dichotomy soon distances the other, it produces the appearance of a 
 main axis with right and left branches : an the extension into 
 an antheridial branch, ar extension into an archegonial branch, y 
 recent dichotomy, o o' older dichotomy in which o' is already per- 
 ceptibly longer, c cupules which arise at the growing end of the 
 midrib and are left upon its upper surface as the stem advances. 
 Drawn with pencil. 
 
 Fig. 3. Flower of radish, greatly enlarged and modified by the 
 growth of Cystopus within it, natural size. The change induced 
 by Cystopus is variable, sometimes single flowers are enlarged, as 
 in this case, sometimes the whole cluster of flowers is changed 
 when the individual flowers remain smaller. This example is 
 larger than the average size. Drawn with pencil. 
 
 Fig. 4. A small fruiting plant of Atrichum, X 2 : the stem bears 
 scale leaves below and foliage leaves above, the base is clothed 
 with rhizoids that simulate roots, st seta, sp capsule sur- 
 mounted by the closely fitting calyptra. The distance the beak 
 extends into the calyptra is indicated. Outline drawing with pen. 
 
 Fig. 5. Flowering head from a vigorous male plant of Atrichum, 
 X 2 : the difference between the perichaetial and foliage leaves is 
 well shown. Drawn with pen. 
 
 Fig. 6. Pod (seed vessel) of Capsella, X 2. Drawn with pen. 
 
PLATE I. Gross Anatomy. 
 
PLATE II. -Minute Anatomy. 
 
EXPLANATION OF PLATE II. 
 
 11.1 ISTRATIONS IN MINUTE ANATOMY. 
 
 Fig. 7. One of the pair of fibro-vascular bundles in a leaf of 
 Pinus, x 400 :/ phloem, .r xylem, sv group of spiral vessels (in 
 other bundles they are often more scattered), ;// ;// rows of paren- 
 chyma cells forming medullary rays containing starch in the xylem 
 and protoplasmic substances in the phloem, r resin duct, f f 
 fibrous tissue with thick walls, small cavities and prominent middle 
 lamellae,/' fibrous cell with lateral pjt,/^ thin-walled parenchyma, 
 // /;' parenchymatous tracheides with bordered pits, tr' face view 
 of the pits on an end wall. The other bundle of the same leaf was 
 at the left side of this one. Drawn with pen. 
 
 Fig. 8. Diagrammatic drawing of a vertical section of leaf of 
 Capsella showing a sorus of Cystopus, X ico : ue upper epidermis, 
 le lower epidermis,/ palisade parenchyma, s spongy parenchyma, 
 fb small fibro-vascular bundle, h hyphae passing between the pali- 
 sade cells and terminating in c the conidiophores which bear the 
 chains of conidia c' . The epidermis is raised, but not yet ruptured, 
 above the sorus. Drawn with pen. 
 
 Fig. 9. Cells of Protococcus after treatment with chlor-iodide 
 of zinc, X 430 : w the thick cell wall, c large chlorophyll bodies, 
 ;/ nucleus with central nucleolus. Drawn with pencil. 
 
 Fig. 10. Diagrammatic drawing of a transverse section through 
 the ovary of Trillium showing one entire carpel, which is shaded, 
 and a portion of the other two, X 12: ww the pair of wings,// the 
 three placentas meeting in the center of the ovary, x xylem and p 
 phloem of the fibro-vascular bundles of which each carpel has one 
 between the wings and one in each placenta, o ovule which re- 
 ceives a branch from the fibro-vascular bundle of the placenta to 
 which it is attached. Drawn with pencil. 
 
 Fig. ii. Diagram to illustrate the theoretical carpellary struc- 
 ture of Trillium, representing a single carpel in transverse section 
 as in fig. 10, and with the same lettering. Drawn with pen. 
 
INTRODUCTION. 
 
 I. INSTRUMENTS, ETC. . 
 
 Following is a list of the instruments and appliances 
 necessary and desirable for use with this manual. 
 Those printed in italics are necessary ; the remainder 
 are desirable but can be dispensed with. 
 
 GROSS ANATOMY. MINUTE ANATOMY. 
 
 Hand lens, 
 Dissecting needles, 
 Razor or scalpel, 
 Glass slips (3), 
 Cover glasses (6), 
 Drawing materials, 
 Holder for lens, 
 Dissecting microscope, 
 Fine forceps, 
 Fine scissors, 
 Camel's-hair brush, 
 Metric rule. 
 
 Compound microscope, 
 Razor or scalpel, 
 Glass slips (12), 
 Cover glasses (24), 
 Fine forceps, 
 Dissecting needles, 
 Drawing materials, 
 Blotting or filter paper, 
 Camel's-hair brushes, 
 Fine scissors, 
 Watch glasses, 
 
 Dropping tube. 
 
 The hand lens should have a magnifying power of 
 eight to fifteen diameters; one of ten or twelve diam- 
 eters is the best. Such a glass costs from 50 cents to 
 $5.00, according to quality and mounting. One costing 
 $1.00 will be found sufficiently good. 
 
 A holder for the lens may be constructed as follows 
 and answers every purpose of a dissecting microscope : 
 
2 INTRODUCTION. 
 
 Take a block of wood about 10 cm. long and 6 cm. 
 wide. Fix upright in the middle of the block about 
 2 cm. from one end a bit of metal rod of 3 to 4 mm. 
 diameter and 6 to 8 cm. high. Bore a hole a little to 
 one side of the center of a smooth cork so that it will 
 slide smoothly on this rod. Bore another hole at right 
 angles to the first through which pass a wire of 7 to 8 
 cm. length. The free end of this wire may be bent into 
 a loop or circle as maybe desired to hold the lens. 1 The 
 lens may be focused by sliding the cork up or down. 
 Cheap loupe holders are also to be had of dealers in 
 optical goods. 
 
 The mounted needles can. be better made than bought. 
 Take two number 8 " sharps," break off about one-third 
 of the needle from the blunt end and grasping the remain- 
 der firmly with a pair of pliers, push the blunt end into 
 a pine pen-holder or any suitable piece of soft wood 
 till firm. The points of the needles should be kept 
 sharp. 
 
 The razor should be of the best quality of steel 
 without any stamped lettering or even etching on the 
 blade, which should be at least 2 cm. wide. The 
 best shape for the blade is to be ground flat on the 
 under side (when held in the right hand with the edge 
 toward one) and hollow on the upper. Next to this 
 shape the "hollow ground " razor is best, provided the 
 thin part of the blade is at least 12 mm. wide and not 
 so thin as to be easily bent. " Extra hollow ground " 
 razors have the blade too thin. 
 
 Glass slips with ground edges may be purchased of 
 any dealer in microscopical supplies or they maybe cut 
 1 Modified from Kingsley, The Naturalist's Assistant, p. 83. 
 
INTRODUCTION. 3 
 
 from clear window glass, or better from photo- 
 graphic plate ; 76 mm. (3 in.) by 25 mm. (i in.) is the 
 standard size. 
 
 Cover glasses must be bought. They should be 15 to 
 20 mm. in diameter or square. No. 2 thickness is pref- 
 erable. 
 
 The compound microscope should be of good work- 
 manship, which can be best secured by buying of some 
 reputable maker. A small low stand is to be pre- 
 ferred. It should have a good fine adjustment and be 
 furnished with two good objectives, viz., a I in., or , 
 and a , \, or , and two eye-pieces, viz., A and C, or if 
 only one, a B. A combination of either eye-piece with 
 the i in., f, or is in this manual designated as a "low 
 power" ; similarly, a combination with the j, , or -J- 
 is known as a " high power." There should also be a 
 camera lucida, and a micrometer ruled in fractions of a 
 millimeter. 
 
 Fine forceps should be of steel, have very slender 
 bent points, and come together accurately. Those used 
 by dentists are excellent. 
 
 A large camels-hair brush \s desirable for dusting off 
 lenses. A small one with long hairs, which tapers to a 
 sharp point when wet, is very convenient for removing 
 sections from the razor. It should be mounted on the 
 small end of a pen-holder, in the large end of which is 
 a short needle. By sticking this in the table the brush 
 may be kept out of the dust and always handy. 
 
 Watch-glasses should have a flat bottom to prevent 
 tipping too easily. Plain individual salt-cellars answer 
 the purpose admirably. 
 
 A dropping-tube is a piece of small glass tubing drawn 
 
4 INTRODVCTtOtf. 
 
 to a point, with a rubber bulb on the larger end. They 
 may be purchased in drug stores under the name of 
 " medicine droppers." 
 
 Fine scissors may be either those made for anatom- 
 ical purposes or small embroidery scissors. The 
 latter answer most purposes well. 
 
 A metric rule is highly desirable. The student 
 should have a pocket rule and should early familiarize 
 himself with the metric system. Metric measures of 
 various styles and prices may be obtained of the Amer- 
 ican Metric Bureau, Boston, Mass. 
 
 The drawing materials required consist of slips or a 
 blank book 8 of unruled paper, hard and soft pencils, 
 pens and ink. For ink drawings the paper may be 
 either sized or unsized, rough or smooth, so long 
 as the ink does not spread, but for pencil drawings 
 the surface must be minutely roughened, and with- 
 out sizing, in order that the plumbago may adhere well 
 and give a soft effect. A quite hard pencil, No. 5, VH 
 or HHHH, of artists' grades, is needed for tracing 
 under the camera lucida, and one slightly softer than 
 used for ordinary writing, No. 2, SM, or B, for com- 
 pleting drawings, especially those in gross anatomy. 
 Ordinary steel pens, preferably those with slender 
 points, and common black ink will suffice, but finer 
 work may be done with lithographic pens and India 
 ink. 
 
 II. REAGENTS. 
 
 The following reagents are necessary for the study 
 of minute anatomy with this manual : 
 
 2 If a book is used it must be so bound that it will lie flat on the table 
 when open. The slips are usually preferred. 
 
IXTRODUCTIOX. $ 
 
 Alcohol, Magenta, 
 
 Potassic hydrate, Glycerine, 
 
 Iodine, Sulphuric acid, 
 
 Chlor-iodide of zinc. Potassic chlorate solution. 
 
 The alcohol used is the commercial article, 95 per 
 cent. pure. 
 
 The potassic hydrate is a 5 per cent, solution of 
 potassic hydrate in distilled water. Sodic hydrate will 
 answer the same purpose. The " liquor potassae " of 
 the U. S. Dispensatory is of this strength and may be 
 purchased of any druggist. 
 
 The iodine is prepared as follows : Dissolve 3 gm. of 
 iodide of potassium in 350 cc. of distilled water ; add I 
 gm. of sublimed iodine. A weaker solution will be 
 useful, viz., potassic iodide 3 gm., distilled water 500 
 cc., iodine I gm. The tincture of iodine diluted till it 
 is a sherry brown color will answer in some cases, but 
 is not so generally useful as the solution recom- 
 mended. 
 
 Chlor-iodide of zinc may be prepared as follows: Dis- 
 solve metallic zinc in concentrated hydrochloric acid 
 until the action ceases ; evaporate to the consist- 
 ency of syrup in contact with metallic zinc ; saturate 
 this with potassic iodide ; add as much iodine as it will 
 take up, with some excess. 3 It is better to keep the 
 solution in a dark place, although in the majority of 
 instances the proper reaction will be secured without 
 this precaution. 
 
 Magenta is a solution of the aniline color of that 
 name. It may be purchased of dealers in microscopi- 
 cal supplies or made as follows : Powder I gm. crystal- 
 3 Poulsen and Trelease, Bot. Micro-Chemistry, p. 8. 
 
6 IN TROD UC TION. 
 
 lized magenta. Dissolve in 160 cc. distilled water, to 
 which I cc. of alcohol has been added. 4 
 
 The best commercial glycerine should be used. See 
 that it is colorless and free from sediment. 
 
 A 75 per cent, solution of sulphuric acid should be 
 prepared by mixing three volumes of c. p. sulphuric 
 acid with one volume of distilled water, being very 
 careful to pour the acid slowly into the water while 
 stirring it. 
 
 The potassic chlorate solution may be prepared as fol- 
 lows : Dissolve 2 gm. potassic chlorate in 5 cc. nitric 
 acid. 
 
 III. USE OF THE MICROSCOPE AND LENS. 
 
 The prime requisite in the use of any optical instru- 
 ment is cleanliness: dirty lenses frequently defeat the 
 very object of their use, namely, clearer vision. Before 
 beginning to work with either the simple or compound 
 microscope, see that the lenses are perfectly clean. 
 When a lens needs cleaning, take a camel's-hair brush 
 and brush away all particles of dust. Then wipe gently 
 with a piece of soft unstarched linen or cotton an old 
 handkerchief is the best breathing upon the surface 
 slightly if necessary to remove the dirt. Too great care 
 can not be taken to avoid scratching the polished surface 
 of the lens ; hence the least possible effective pressure 
 should be used when wiping it. If properly handled 
 after they have once been cleaned, lenses will seldom 
 need any thing but brushing. One should avoid with 
 the greatest care touching the surface of a lens with 
 
 4 Huxley and Martin, Biology, p. 269. 
 
INTRODUCTION. 7 
 
 the fingers, as finger marks are difficult to remove : no 
 matter how clean the skin, the oil from it will adhere to 
 the glass and can only be perfectly removed by wiping 
 with linen moistened with alcohol. 
 
 When the lens is held in the hand to examine ob- 
 jects, rest the hand holding the lens on the hand hold- 
 ing the object. They will then tremble together. The 
 eye should be as close to the lens as possible in order 
 to obtain a wider field of view. 
 
 In using the compound microscope the front only of 
 the objective and both surfaces of both lenses of the 
 eye-piece need cleaning. If the eye-piece be dirty there 
 will be specks in the field of view when there is no ob- 
 ject on the stage. These can be made more apparent 
 by turning the eye-piece in the tube while looking 
 through it. In like manner by partly unscrewing the 
 eye lens and turning it, it may be discovered whether 
 the eye lens or field lens is dirty. If the front of the 
 objective be dirty it will be manifested by a dimness 
 and want of definition of the outlines of objects, affect- 
 ing the whole field of view. 
 
 In focusing with the high power of the compound 
 microscope, first rack the objective down as close to the 
 cover-glass as possible while watching it from one side. 
 Then look through the tube, rack slowly back and 
 watch for the coming of the object into view. 
 
 Never rack downwards while looking through the 
 tube unless the object be in view. 
 
 Do not use the fine adjustment until the object is 
 nearly in focus with the coarse. 
 
 Raise the objective slightly before placing or remov- 
 ing a slide. 
 
8 INTRODUCTION. 
 
 An object is examined by " direct " light when it is 
 examined by the light which falls upon its surface with- 
 out passing through it. This is the common method 
 with the hand lens. 
 
 An object is examined by " transmitted " light when 
 the light passes through it before entering the eye. 
 This is the common method with the compound mi- 
 croscope. Ordinarily, when transmitted light is used, 
 direct light should be cut off as far as possible. 
 
 An object is examined by " oblique " light when the 
 light passes through it so obliquely that only that re- 
 fracted by the object enters the eye. It therefore ap- 
 pears light against a dark ground. 
 
 IV. SECTION CUTTING. 
 
 Sections. A section is a very thin slice taken from the 
 interior of any organ. It should be of as nearly equal 
 thickness in all parts as possible. The term " slice " is 
 used to designate a thin piece cut from the surface of 
 any organ. 
 
 By a transverse section is meant one at right angles 
 to the long axis of the object. Unless care is exercised 
 the surface from which the sections are being cut will 
 become inclined. Especially is this likely when the 
 object is large or is supported in pith. The pith stick 
 should be trimmed down at the end so as to leave only 
 enough to support the object. The chief cause of the 
 tendency to become inclined is that the under side of 
 the razor is not flat ; hence the larger the object, the 
 more likely the transverse sections are not to be truly 
 transverse. 
 
 By a longitudinal section is meant one which is 
 
INTRODUCTION. 9 
 
 parallel to or includes the long axis of the object. It is 
 evident that longitudinal sections of all cylindrical ob- 
 jects may be either radial or tangential. A radial 
 section is one lying in the plane of a radius. A tangen- 
 tial section is one parallel to a plane tangent to the 
 cylinder. 
 
 Longitudinal sections are much more difficult to 
 make than transverse and they are nearly or quite use- 
 less unless truly longitudinal. 
 
 The razor. The secret of making good sections 
 lies in having and keeping a sharp razor. No 
 amount of skill can make a dull razor cut a thin 
 section. 
 
 The edge of the razor must be free from nicks. This 
 can be determined by looking at the profile of the edge 
 against a bright light with a lens. Nicks, if small, can 
 easily be taken out on a hone. 
 
 The razor should be stropped often. It is easier to 
 keep it from getting dull than to sharpen it after it has 
 become so. If its edge is free from nicks and it will cut 
 a hair of the head 2 cm. from where it is grasped by the 
 fingers, it is in good condition. 
 
 After using the razor be careful to see that no mois- 
 ture or plant juices are left on the blade; they will 
 surely rust it if allowed to remain. 
 
 Holding specimens. Large specimens of which 
 sections are to be cut may easily be held in the 
 fingers. They should be held vertical, grasped 
 by the fore-finger and thumb of the left hand 
 so that the razor blade may rest on the cor- 
 ner of the fore-finger, and the remainder of the hand 
 be out of the way below. 
 
10 INTRODUCTION. 
 
 Small objects should be placed in a piece of elder or 
 sunflower pith in which a median longitudinal slit has 
 been made, deep enough to allow the ends to spring as 
 far apart as necessary to receive the specimen, between 
 which it is to be firmly held. The pith is then to 
 be grasped as a large specimen for cutting. If alcoholic 
 specimens are being used the pith should be pre- 
 viously soaked in alcohol, and if fresh material, in 
 water. 
 
 Cutting. Grasp the razor firmly with the right hand 
 where the blade joins the handle, bracing the blade by 
 resting the thumb against the tang. Hold the razor hor- 
 izontal, rest the under side of the blade against the corner 
 of the fore-finger and cut toward you, pushing the razor 
 from point to tang or drawing it in the opposite 
 direction, using as much of the blade in cutting as 
 possible. 
 
 If the object be flat and thin, as a leaf, let the razor 
 edge pass through it at an angle of 20 to 30 to its 
 length. 
 
 If alcoholic specimens are being cut, the razor blade 
 should be flowing with alcohol. The oil usually on the 
 blade from stropping will prevent the alcohol from run- 
 ning off, unless the blade be considerably inclined. If 
 fresh material is used the razor should be dipped in 
 water. The object of the operation in both cases is to 
 prevent the section from becoming dry. Should it do 
 so, it will inevitably contain air bubbles when mounted, 
 which will unfit it for examination. 
 
 Removing the sections. The most convenient thing 
 for removing sections from the razor is a small camel's- 
 hair brush, which, when wet, tapers to a sharp point. 
 
INTRODUCTION. li 
 
 With such a brush a section may easily be picked up 
 from the water or alcohol, in which it ought to be 
 floating on the razor, and transferred either to the slide 
 or to a watch glass. An easier way of removing sec- 
 tions which are to be transferred to a watch glass, is 
 to wash them down to the point of the razor, and then 
 dip the point of the blade in the liquid in the watch 
 glass. 
 
 Always cut a number of sections half a dozen or 
 more at once. One or more may prove good. 
 
 V. MOUNTING. 
 
 Previous to mounting any specimens, it must be seen 
 that the slide and cover glass are perfectly clean. 
 Nothing is better for cleaning slides and covers than a 
 clean linen handkerchief, which should be used for this 
 purpose alone. The cleaning of the slide is a simple 
 operation ; the cleaning of the cover requires more care, 
 to prevent breaking. Having dipped the cover in clean 
 water, take it between the thumb and fore-finger, over 
 which a single thickness of the handkerchief has been 
 thrown. Wipe gently, using the fingers of the other 
 hand to keep it in place. The surfaces of the cover 
 should be perfectly cleaned, so that when light is 
 reflected from them, no oiliness or dust is visible. 
 Having cleaned the cover, lay it down in some clean 
 place, with one edge projecting slightly, so that it can 
 be readily picked up, or stand it on edge against some 
 support. 5 Having placed the desired specimen 
 
 5 A very convenient receptacle for covers, whether clean or dirty, is 
 made by sawing several grooves in a block of wood, and nailing across 
 the ends of the grooves a thin strip. In these grooves the covers rest on 
 edge. A similar arrangement is useful for slides. 
 
1 2 IN TROD UCTIOtf. 
 
 in the center of the slide in a drop of water, 
 grasp the edge of the cover firmly with the fine 
 forceps, breathe on the under side, hold it in a slanting 
 position over the drop of water, place the lower edge 
 in the edge of the drop, and lower it gradually on the 
 water. The condensed moisture of the breath insures 
 more ready contact of the water with the cover, and 
 lowering the cover slantwise gives opportunity for the 
 escape of air from under it. 
 
 If air bubbles appear in the mounting, they are due 
 to one of two reasons : either (i) the cover glass was 
 not clean, or (2) it was dropped instead of being low- 
 ered to the slide. Of these the first is the more com- 
 mon cause of air bubbles. They may sometimes be 
 removed by lifting one edge of the cover with a needle, 
 while the other is prevented from slipping, and then 
 lowering again. Sometimes it will be necessary to 
 remove the cover, clean and replace it. 
 
 If the bubbles appear in the specimen itself, they are 
 probably caused by allowing the section to dry partly 
 before mounting. They may usually be removed by 
 taking off the cover and treating the specimen with 
 alcohol. 
 
 The worker should not be content to let bubbles 
 remain. 
 
 Another difficulty is sometimes encountered, when 
 it is attempted to mount several sections under the 
 same cover, in the floating out of one or more. This 
 is usually due to an excess of water. The remedy is to 
 take up the cover, absorb some of the water with filter 
 paper, and re-cover. 
 
 After covering specimens, soak up the superfluous 
 
INTRODUCTION. 13 
 
 liquid sufficiently to prevent the cover floating when 
 the slide is inclined. 
 
 VI. APPLYING REAGENTS. 
 
 Stains are most conveniently applied by placing a 
 drop of the liquid at the edge of the cover, and allow- 
 ing it to run under, hastening the process when desired 
 by placing a strip of filter paper at the opposite edge. 
 If the stain does not reach all parts of the specimen, 
 the cover glass may be slightly raised. It is quite 
 important in many cases to watch the action of reagents. 
 In such a case they should be applied with the stage of 
 the microscope horizontal. Time may be saved when 
 it is necessary to examine specimens in potash, by 
 placing a drop of potash on the slide, and mounting 
 directly in that medium. In all cases, as soon as the 
 specimens have become clear, the potash should be 
 washed out with water: otherwise the cell walls swell 
 excessively, and many points become indistinguishable. 
 It should be remembered in examining specimens 
 treated with potash that many cell walls are somewhat 
 swollen, and that the longer they remain the greater 
 the swelling becomes. 
 
 Glycerine is one of the most useful media for clear- 
 ing, and at the same time preserving specimens for 
 prolonged examination. Whenever it becomes desir- 
 able to preserve specimens from one day to another, a 
 drop of glycerine should be applied to the slide, so 
 that it just touches the edge of the cover, and the slide 
 laid away in a horizontal position. As the water or 
 alcohol evaporates, the glycerine will run under the 
 cover. The excess may be wiped off with a damp rag 
 
1 4 IN TROD UCTION. 
 
 after a few hours. Specimens may be mounted directly 
 from alcohol or water in glycerine, but the saving in 
 time will not be material, unless it is known that the 
 specimens are good, before mounting. Care must be 
 taken that the glycerine does not overspread the cover, 
 which, under such condition, must be taken off and 
 cleaned. Most specimens may remain in glycerine any 
 length of time without deterioration, and will become 
 clearer and clearer all the time. Care must be taken to 
 keep the specimens thus preserved free from dust. 
 They must be handled cautiously, lest the cover be 
 shoved off. If desired, specimens which have been 
 preserved in glycerine, may be permanently mounted, 
 by simply running a ring of shellac cement around the 
 cover. 6 
 
 The greatest care must always be exercised to pre- 
 vent reagents from coming in contact with the stand 
 of the microscope or the lenses, as most of them attack 
 the lacquer of the brass work, and some the brass. 
 The chief danger arises from a failure to remove the 
 excess of the reagent, which then collects at the lower 
 edge of the slide when the microscope is used in an 
 inclined position, and runs off on the stage. Sulphuric 
 acid behaves in the same way even when the excess 
 is once removed, if it is allowed to remain any length 
 of time, because it absorbs moisture from the air. 
 
 Boiling specimens in the potassic chlorate solution 
 should not be done in the same room with the micros- 
 cope as the liquid and its fumes are intensely corro- 
 sive. 
 
 6 For directions for making this cement, see Am. Mo. Mic. Jour., v t 
 (1884), p. 131. Similar cements may be bought. 
 
IN TR OD UC TION. 1 5 
 
 VII. CARE AND USE OF MATERIAL. 
 
 Throughout the directions for laboratory work it is 
 understood that material preserved in alcohol will 
 answer unless otherwise stated. In many cases only 
 alcoholic specimens are usable and in other cases only 
 fresh specimens. 
 
 Do not tear up specimens needlessly. 
 
 Examine a specimen thoroughly and see as much as 
 possible before dissecting. 
 
 Do not begin dissecting a part until it is decided 
 what to look for and where to look for it. 
 
 Be economical ; chiefly because it is a good habit, 
 secondarily because material costs time, or money, or 
 both. 
 
 Save the pieces ; they may be useful in future work : 
 it is easy to throw away ; it is more difficult to gather. 
 
 Preserve all sections and other preparations until the 
 study of the plant is completed. 
 
 When the specimens are mounted in water be care- 
 ful lest they become dry by the evaporation of the 
 water. It can be most conveniently replaced by plac- 
 ing a brush charged with water at the edge of the 
 cover opposite the area of air. As soon as the air is 
 displaced the brush should be removed. 
 
 When studying particular tissues in a section the 
 thinnest parts of each tissue should be selected. It is 
 rare that a section is so uniform that the tissues are 
 equally well shown in all parts of it, and different tissues 
 must not infrequently be looked for in different sec- 
 tions. It is best therefore to look well over the speci- 
 mens before settling to the study of any tissue. 
 
 In order to obtain a clear conception of the shapes 
 
1 6 INTRODUCTION. 
 
 of the cells of a particular tissue, it is indispensable that 
 the student carefully compare the transverse and longi- 
 tudinal sections of the cells. Moreover the longitudi- 
 nal sections must be compared with the transverse to 
 determine their position. 
 
 It frequently becomes necessary to examine a toler- 
 ably thick object. In such a case, very different views 
 of the object will be obtained as the focusing screw of 
 the fine adjustment is moved. It must be remembered 
 that a good objective gives a clear image of only a 
 single plane at one time, though adjacent images 
 modify this somewhat. Hence it is easy to determine, 
 knowing in which direction the objective is moved by 
 the focusing screw, whether one object is above or 
 below another. 
 
 The use of the fine adjustment must be learned as 
 soon as possible and must be assiduously practiced. 
 The finger should be kept on the fine adjustment most 
 of the time when using high powers, and nothing 
 allowed to escape the vision which the fraction of a 
 turn would reveal. 
 
 VIII. DRAWING. 
 
 In the systematic examination of an object two kinds 
 of memoranda should be made, descriptions and 
 drawings. The value of the former is usually conceded, 
 but that of the latter is often deemed too slight to re- 
 pay the trouble. The importance of drawing can not, 
 however, be too strenuously urged, and the difficulty 
 and tediousness of execution, which will largely dis- 
 appear with practice, should never be offered as an 
 excuse for its neglect. 
 
INTRODUCTION. l^ 
 
 Drawing may represent the object with various 
 degrees of fidelity. At one extreme is the diagram 
 (see fig. i), which only aims to give the relative posi- 
 tions or sizes of the several parts, or some other feat- 
 ure. At the other extreme the drawing is as close a 
 counterpart of the object seen as the person who draws 
 it is capable of producing (see fig. 3). Whether a par- 
 ticular object shall be drawn in one way or the other, 
 or in some intermediate way, must be determined 
 by the nature of the object and the end to be attained 
 by the study. 
 
 The usual tendency is to make drawings too small ; 
 they should be large enough to show all parts dis- 
 tinctly without close scrutiny. 
 
 Drawings may usually be satisfactorily made in out- 
 line, or with very little shading, as in fig. 4 or 6. They 
 are most easily drawn with a soft pencil on heavy, 
 unsized and slightly calendered paper, producing the 
 effect in fig. 3 or 10, but are not permanent ; rubbing 
 readily defaces them, unless treated to a fine spray of 
 colorless shellac dissolved in alcohol, which may be 
 applied with an atomizer, such as is used for perfumery. 
 Ink drawings are to be preferred fortheirdurability and 
 distinctness. When ink is used, the main features of the 
 drawing should first be lightly sketched with a hard 
 pencil, and the pencil marks erased after the ink is dry. 
 
 Drawings in gross anatomy should be the exact size 
 of the object, or some multiple of it. Record the 
 amount of linear enlargement by a number placed 
 at one side of the drawing with an oblique cross 
 prefixed. 
 
 In the directions for laboratory work in gross 
 
1 8 INTRODUCTION". 
 
 anatomy the number of drawings has been mostly left 
 to the discretion of the student. 
 
 In minute anatomy the points at which drawings 
 may most profitably be made are carefully noted. In 
 many instances, however, it is so difficult to secure a 
 wholly satisfactory section to show certain structures, 
 that they should be drawn whenever found in good 
 condition, without regard to the directions. 
 
 Drawings in minute anatomy may be either free- 
 hand or with camera lucida. In free-hand drawing the 
 student is especially cautioned against making them 
 too small, which is a very common fault. In the out- 
 lines for work it is expected that accurate drawings be 
 made unless a diagram or diagrammatic drawing is 
 called for. A diagram (fig. 11) shows only a single 
 special feature, or at most two or three, while a dia- 
 grammatic drawing (fig. 8 or 10) shows all the chief 
 features, but does not take note of smaller matters, 
 such (e. g.) as distinguish the several cells of the same 
 tissue. When an accurate drawing is to be made, each 
 individual cell should be drawn as carefully as if it 
 were the whole object. When an accurate drawing 
 includes considerable tissue, time may be saved by 
 indicating the boundaries between the tissues by dot- 
 ted outlines, and only cells enough filled in to show 
 the character of the tissues. 
 
 In order to draw to scale with the microscope it is 
 necessary to use a camera lucida. The magnification 
 is thus determined : place a micrometer on the stage 
 of the instrument in the same position as an object, 
 adjust the instrument as for drawing, and laying a 
 common rule on the drawing paper read off the dis- 
 
IN TROD UCTION. 1 9 
 
 tance that the image of one division of the stage 
 micrometer covers on the rule. If, for instance, a tenth 
 of a millimeter of the stage micrometer covers five 
 centimeters (five hundred tenths of a millimeter), any 
 drawing under the same adjustment will be magnified 
 five hundred times. -Always mark the number of 
 times magnified at the side of the drawing as in gross 
 anatomy, thus, x 500. 
 
 The distance from the drawing-paper to the reflecting 
 surface of the camera lucida should be about the same 
 as from the latter to the outer lens of the object glass, 
 in order that the drawing may properly represent the 
 magnifying power of the instrument. Ten inches has 
 been adopted as the standard length of tube. 
 
 Trace the image first with a hard pencil, and then 
 go over it with ink before the object is removed from 
 the instrument in order to correct any errors made by 
 the pencil. 
 
 It is not an easy matter to draw accurately with the 
 camera lucida, owing to the difficulty in seeing both 
 the image and the pencil point distinctly at the same 
 time. Much depends on the relative amount of light 
 received by the eye from the instrument and from the 
 drawing-paper. If the pencil point does not show 
 clearly, there should be more light on the paper, and 
 if the image is not clear, more on the object. 
 
 Invariably accompany each drawing with a full expla- 
 nation. 
 
 IX. BOOKS OF REFERENCE. 
 
 It should be the aim of the student to find out all 
 that he can about the plant in hand with as little assist- 
 
20 INTRODUCTION. 
 
 ance as possible or without any. This requires patient 
 and thorough work. When done, however, and draw- 
 ings and notes have been fully recorded, it will be 
 advantageous to compare the work with the published 
 observations of others, and if any points have been 
 overlooked or misunderstood, to go over the ground 
 again. 
 
 The following general treatises will be found suita- 
 ble for preliminary consultation, and when possible 
 should be constantly at hand on the laboratory shelves : 
 Gray's Structural Botany, Goodale's Physiological 
 Botany, Bessey's Botany for High Schools and Col- 
 leges, Sachs' Text Book, 2nd Eng. edition, Prantl and 
 Vines' Text Book of Botany, DeBary's Comparative 
 Anatomy of Phanerogams and Ferns, Strasburger's 
 Das botanische Practicum, Poulsen and Trelease's 
 Botanical Micro-Chemistry. 
 
 If the student becomes interested in any particular 
 direction, the references given in the annotations, 
 together with those to be found in such of the works 
 just named as may be at hand, will usually give him a 
 fair start in tracing the literature of the subject, and 
 becoming acquainted with what has already been ascer- 
 tained in regard to it. This will indicate wherein 
 present information is defective, and enable him to 
 direct his labors toward a profitable increase of the 
 total sum of knowledge. 
 
 The references have been preferably to works most 
 likely to be at the student's command, whenever these 
 have contained a sufficiently full treatment, this doubt- 
 less tending more to accomplish the desired object 
 of interesting the student and leading him on to 
 
INTRODUCTION. 21 
 
 independent work, than references in all cases to the 
 original sources of information. Less accessible works 
 have often been cited to introduce the student at 
 once to the most complete treatment of the subject. 
 A few citations are for the sake of authority. 
 
 Many of the memoirs and articles cited in apparently 
 inaccessible foreign journals and proceedings of socie- 
 ties may, however, be bought separately of foreign 
 dealers (R. Friedlander & Sohn, Berlin N. W., Ger- 
 many, and many others). A very moderate outlay 
 will thus enable one to consult numerous valuable 
 writings. 
 
 No apology need be offered for referring in an 
 elementary work to writings in foreign languages, for 
 unless the student carries his researches outside this 
 manual he will have no occasion to use them, and if 
 he does do so he can not go far without being obliged 
 to use them. It is not often possible in fact to treat a 
 subject exhaustively in the departments of botany 
 covered by this handbook without a knowledge of 
 German and French writings at least. 
 
 But if the references given among the annotations 
 are never used, they will still serve a good purpose in 
 impressing upon the learner that he is only upon the 
 threshold of the study, and that the facts which he 
 seems to be gathering so thoroughly are in most cases 
 to be found more fully and accurately set forth in the 
 great storehouse of learning beyond. 
 
GREEN SLIME. 
 
 Protococcus viridis Ag. 
 
 PRELIMINARY. 
 
 THE plant selected to illustrate the simplest phase'of 
 vegetable life is found in all parts of the United 
 States, and even throughout the world. It grows 
 upon the surface of various objects, being often so 
 abundant as to give them a conspicuous green color, 
 especially upon the north side of old fences, barns, 
 and the trunks of trees, becoming more noticeable 
 after a few days of damp weather. There are several 
 other closely related species that may be used, in 
 fact almost any unicellular green plant will answer, 
 but this is the one most likely to be gathered. Some 
 kinds of unicellular plants, like Gl&ocapsa, have a 
 sheath or envelope outside the cell proper, not found 
 in Protococcus, a fact to be borne in mind by the 
 student if such plants are used. Pieces of bark or 
 wood bearing the alga may be kept dry for use, and 
 will give a fresh appearance when moistened with 
 water, and even retain vitality for a year or two. 
 
 It is quite likely that the plants known under the 
 name of Protococcus are but early forms of some more 
 complex algae 1 , but, however this may be, they serve 
 
 1 Bessey, Botany, p. 219 ; Wood, Fresh-Water Algae of North 
 America, p. 10 ; Sachs, Text-Book of Botany, 2nd Eng. ed., p. 248 ; 
 Cienkowski, Bot. Zeit. 1876, p. 17. 
 
PROTOCOCCUS VIRIDIS. 23 
 
 quite as well as any to illustrate the simplest kind of 
 plant life. 
 
 To complete the following study it will be necessary 
 to have pieces of wood bearing the Protococcus ; iodine ; 
 chlor-iodide of zinc ; and alcohol. 
 
 LABORATORY WORK. 
 
 GROSS ANATOMY. 
 
 Taking either a fresh or dried specimen, notice 
 
 1. The color. 
 
 2. The evenness with which the plant overspreads the 
 supporting surface. 
 
 Using a lens, notice 
 
 3. The pulverulent appearance, as if dusted or sanded 
 upon the surface. 
 
 4. The appreciable thickness reached in some spots, 
 causing it to separate in scales in the dried specimen. 
 
 Mount, and observe 
 
 5. The dust-like particles' 1 into which it separates. 
 
 6. The varying size of the particles. 
 
 Place a piece of bark with the Protococcus in a small 
 quantity of alcohol, after an hour or more notice 
 
 7. The color imparted to the alcohol by the coloring 
 matter of the plant, the chlorophyll. 3 
 
 MINUTE ANATOMY. 
 
 Under high power, notice 
 
 8 Care must be taken not to confound them with air bubbles, which 
 are often numerous when a dried specimen is used. 
 
 8 Some less common forms of unicellular algae are red or purple from 
 additional coloring matter. 
 
24 GREEN' SLIME. 
 
 1. The individual cells; either single or associated in 
 families. 
 
 2. The size of the cells ; some small, some several times 
 larger. 
 
 3. The shape ; when free and when in families. 
 
 4. The cell contents ; more or less granular, and always 
 green from the presence of chlorophyll. 
 
 5. The colorless cell- wall surrounding each cell. 
 Press upon the cover-glass with a back and forth move- 
 ment, and the walls to many of the cells and cell-families 
 will be ruptured and their contents ejected, when the 
 wall can be easily studied. 
 
 Stain with iodine and notice 
 
 6. The brownish-yellow color given the contents of the 
 cell, showing the presence of protoplasm. 
 
 Stain a freshly mounted specimen with dilute chlor- 
 iodide of zinc, and after an hour or two 4 notice 
 
 7. The two to several closely packed bodies of definite 
 outline, usually overlapping, forming the green part 
 of the cell, the chlorophyll bodies, best seen in the 
 largest, single, round cells. 5 
 
 8. The small round body nearly in the center of the cell, 
 or in recently divided cells near the partition wall, the 
 nucleus. 6 
 
 9. Occasionally a clear space between the chlorophyll 
 bodies and the cell wall, occupied by \hzprotoplasm. 
 
 10. Draw a few cells showing chlorophyll bodies and 
 nuclei. 
 
 4 If the cells are properly stained they will usually remain green, but of a 
 brighter and more bluish hue. 
 
 5 There is danger of mistaking delicate partition walls of young cells, 
 which the reagent has thickened and made visible, for the boundaries of 
 the chlorophyll bodies. 
 
 6 Under higher power yet a central dot to the nucleus, the nucleolus, 
 may be detected. 
 
PROTOCOCCUS VIRIDIS. 25 
 
 11. The cell multiplication: examine various specimens 
 and trace the successive stages in the division of a 
 single cell to form a cell family. 
 
 12. Illustrate the cell multiplication by drawings. 
 
 ANNOTATIONS. 
 
 Protococcus is a unicellular plant, for each cell 
 performs individually the various functions pertaining 
 to plant life ; and this is true whether the cells remain 
 single or become associated into small families. 
 
 The cell is the unit from which all plants, however 
 complex, are built up. 
 
 The most essential part of the cell is the protoplasm, 
 a colorless semi-fluid substance, which in this instance 
 is masked by the green chlorophyll. It is the only 
 really living, active agent in this, as well as in all other 
 plants. Its presence here is made manifest by the 
 characteristic yellowish-brown color given by iodine. 
 
 The nucleus (see fig. 9 n) is a special form of the pro- 
 toplasm to be seen in most plant-cells. As its division 
 usually precedes that of the cell, it has generally been 
 regarded as in some way necessary to the latter pro- 
 cess. The investigations of Schmitz, Strasburger 7 and 
 others go to show, however, that the two processes 
 are distinct, and that the nucleus, instead of being 
 related to cell division, holds an intimate and probably 
 essential relation to the life of the protoplasm. 
 
 The protoplasm takes on another form in the chlor- 
 ophyll bodies 8 (see fig. 9 c). These consist of a proto- 
 
 7 Zellbildung und Zelltheilung, p. 371. 
 
 8 Cf. Strasburger, Das botanische Practicum, p. 350 ; Schmiu, 
 Chromatophoren der Algen. 
 
26 GREEN SLIME. 
 
 plasmic body containing the green chlorophyll pigment. 
 The surrounding protoplasm by the aid of the chloro- 
 phyll is able to convert inorganic into organized matter, 
 a function wanting in all animals, with the exception 
 of a few of the lowest, like Hydra and Euglena, and 
 also wanting in some plants, e. g. fungi and colorless 
 parasites. 
 
 The solid, firm, and nearly colorless cell-wall is a 
 product of the protoplasm consisting essentially of 
 cellulose, and serves as a protection to the protoplasm. 
 The fine granules seen in the protoplasm, are largely 
 food materials produced by the cell in excess of what 
 the present needs require. 
 
 The multiplication of the plant by cell-division is a 
 very common method throughout the vegetable king- 
 dom. 8 The nucleus first disappears and two nuclei are 
 formed in its stead. The protoplasm then divides 
 itself, keeping a nucleus in each part, and a wall is 
 formed between. The two cells thus produced soon 
 attain the size of the original cell, when they in turn 
 divide into two, but usually by a partition at right 
 angles to the last, and so on. The cells thus formed 
 either soon become separated, or retain a mechanical 
 union. 
 
 Another method of multiplication is by the produc- 
 tion of zoospores. 10 The plastic contents of a cell, 
 either as a whole or divided into several parts, escapes 
 from the cell wall, each mass pushes out a pair of 
 delicate protoplasmic filaments or cilia, which moving 
 
 9 Cf. Bessey, Botany, p. 36, for a statement of the different methods 
 by which new cells are formed. 
 
 10 Cf. Huxley and Martin, Elementary Biology, p. 12, 15 ; Howes, 
 Atlas of Elementary Biology, p. 74, pi. xviii. 
 
PROTOCOCCUS VIRIDIS. 27 
 
 rapidly back and forth propel the naked protoplasm 
 through the water. The motion and form give a 
 strong resemblance to some of the simplest animals, 
 hence the name of animal-like spores. After a time 
 they come to rest, draw in the cilia, secrete a cell-wall, 
 and become ordinary Protococcus cells. Sometimes 
 the protoplasm does not free itself from the cell wall, 
 but contracts somewhat, the cilia are protruded through 
 the wall and the mass propelled as just stated. The 
 production of zoospores at a specified time, as for a 
 class demonstration, is attended with so much uncer- 
 tainty that their study has been omitted from the 
 laboratory work. This method of asexual multiplica- 
 tion will be studied later under more favorable condi- 
 tions in Cystopus. 11 
 
 11 At p. 47- 
 
DARK GREEN SCUM. 
 
 Oscillaria tennis Ag. 
 
 PRELIMINARY. 
 
 THE color of Oscillaria, almost any species of which 
 may be used, is generally sufficient to enable one to 
 distinguish it at sight. Its dark blue-green is in 
 marked contrast with the yellow-green of most other 
 plants which form scums. It is very common on 
 stagnant water, often forming patches of scum thirty 
 centimeters (a foot) or more in diameter, which becom- 
 ing loaded with dust finally sink to the bottom. It is 
 also very common about watering troughs, along street 
 gutters, at the outlet of drains, on wet rocks,- giving 
 them a slippery surface, in the greenhouse, and especi- 
 ally in water containing a small amount of garbage. 
 It can usually be grown indefinitely in an open jar, by 
 supplying the water as it evaporates, or with less 
 trouble, when once established, in an unstoppered bottle, 
 in which a small twig or flower stem of some sort is 
 inserted to provide nutriment. The plants are often 
 to be found in winter in as good condition as in sum- 
 mer. The study should be made upon growing plants 
 when possible, but specimens dried on paper or mica 
 will serve quite as well, except to show the oscillating 
 movements, which are characteristic of the group to 
 which Oscillaria belongs. 
 
OSCILLARIA TEN U IS. 29 
 
 Only the following material is necessary for the 
 study: fresh plants, or in their absence dried speci- 
 mens; a dried mass half as large as a pea; and alco- 
 hol. 
 
 LABORATORY WORK. 
 
 GROSS ANATOMY. 
 
 1. Examine a small mass of the living plant which has 
 been allowed to remain undisturbed for several hours 
 in a watch-glass of water ; notice 
 
 a. The deep blue-green color. 
 
 b. The hair-like unbranched filaments, radiating 
 from the central mass. 
 
 2. Sketch the plant as it appears in the watch-glass. 
 
 3. Mount a fragment and observe the uniform diameter 
 and appearance of the filaments. 
 
 Pulverize a mass of the plant that has been thoroughly 
 dried, place in a test-tube or vial with nearly twice 
 the bulk of water, and after ten to twenty-four hours 
 notice 
 
 4. The color of the solution when seen by transmitted 
 light and the very different color by reflected light, 
 indicating the presence of phycocyanine. 
 
 Pour off the supernatant water, add the same amount of 
 
 alcohol instead, and after an hour or more notice 
 
 
 
 5. The yellow-green color imparted by the chloro- 
 phyll. 
 
 MINUTE ANATOMY. 
 
 A. GENERAL CHARACTERS. Under a low 'power, 
 notice 
 i. The color. 
 
30 DARK GREEN SCUM. 
 
 2. The numerous filaments of uniform diameter, destitute 
 of branches. 
 
 3. Study the movements. 
 
 B. THE INDIVIDUAL FILAMENT. Under high 
 power, notice 
 
 1. The structure in detail, as follows : 
 
 a. The rounded extremities of uninjured filaments. 
 
 b. The outline of an uninjured apex, whether attenu- 
 ated or not, and whether bent to one side or 
 straight. 
 
 c. The delicate lines of the partition walls crossing 
 the filament and dividing it into very small 
 cells. 
 
 d. The comparative length and breadth of the 
 cells. 
 
 e. The granular contents, and their distribution in 
 the cell. 1 
 
 /. The delicate colorless sheath to be seen extending 
 beyond the green cells at some torn end of a fila- 
 ment, and on which may sometimes be detected 
 transverse lines indicating the former position of 
 the end walls of the cells. 
 
 2. The turgidity of the cells: notice that 
 
 a. The transverse walls in an uninjured filament are 
 plane, while 
 
 b. The last cell of an injured filament is bulged out- 
 ward, making the outer transverse wall convex, 
 the pressure from within not being counterbal- 
 anced from without. 
 
 3. Draw one or more filaments. 
 
 1 In some species the granules are collected along the partition walls. 
 
OSC ILL ARIA TEN U IS. . 31 
 
 ANNOTATIONS. 
 
 If the structure of Oscillaria be carefully compared 
 with that of Protococcus more points of resemblance 
 will be found than appear at first sight. New cells are 
 formed by the process of division, as in Protococcus, 
 but the partition walls are always parallel and in one 
 direction, which disposes the cell families in filaments. 
 The individual cells have thin walls, the office of pro- 
 tection being relegated to the sheath. The sheath, 
 which is formed from the outside walls of the cells by 
 a modification of the outer portion, is a structure that is 
 mostly confined to certain groups of the lower plants, 
 although it has some analogies with the cuticle of the 
 higher plants. The protoplasm is homogeneous, and 
 not differentiated into chlorophyll bodies and nucleus 
 as in Protococcus ; chlorophyll is, however, present, 
 evenly distributed through the protoplasm, but no 
 nucleus has yet been discovered. The study of the pro- 
 toplasm and chlorophyll is much obscured by the pres- 
 ence of the peculiar coloring matter, phycocyanine, 
 characteristic of the Cyanophycece to which Oscillaria 
 belongs. It is this that gives the deep blue-green color 
 to the plants, enabling one to distinguish them at sight. 
 It is insoluble in alcohol, but soluble in water when the 
 plants are dead, while chlorophyll is soluble in alcohol, 
 but not in water; hence, digesting the dead plants with 
 water removes the phycocyanine, and digesting with 
 alcohol removes the chlorophyll. 2 This blue color is 
 often seen on the sides of vessels in which Oscillaria 
 has remained so long as to die, and also staining the 
 8 Cf. Sachs, Text-book of Botany, 2nd Eng. ed., p. 246, 766. 
 
32 . DARK GREEN SCUM. 
 
 herbarium sheets on which specimens have been 
 dried. 
 
 The cells are assisted in keeping together by the 
 investing sheath, into which they are packed like a roll 
 of lozenges in their case. This structure, together with 
 the community of action exhibited in producing the 
 peculiar oscillating and nutating movements, makes it 
 evident that the cells of each filament have a certain 
 dependence upon each other, although at the same 
 time each is capable of independent existence. It may 
 be that the smallness of the cells and the thinness of 
 their walls is in some way correlated to this unity of 
 function. It is not yet definitely known how the move- 
 ments in Oscillaria are produced. 3 
 
 Turgidity is a characteristic of living cells. It is the 
 means by which the soft parts of plants are enabled to 
 keep their form, and otherwise to serve their purpose. 
 It is brought about by the strong imbibition power. of 
 the protoplasm, causing water to be taken up until 
 a considerable internal pressure is created. 4 
 
 3 Engelmann has discussed several theories, and suggested that the 
 movements are brought about by vibratile thread-like extensions of the 
 protoplasm through the cell walls. Bot. Zeit. 1879, p. 49 According 
 to Hansgirg it is due to an osmotic action of the protoplasm. Bot. 
 Zeit. 1883, p. 831. 
 
 4 Cf. Bessey, Botany, p. 166. 
 
COMMON POND SCUM. 
 
 Spitogyra quinina Kiitz. 
 
 PRELIMINARY. 
 
 THE members of this genus are abundant in stagnant 
 water everywhere, forming bright yellow-green scums of 
 great extent, sometimes diffused beneath the surface, or 
 in running water attached to stones. They may be read- 
 ily distinguished from all other scum-producing plants, 
 except from a few of their close allies, in having a slip- 
 pery feel, and being composed of long unbranched fila- 
 ments, which string out like wet hair when withdrawn 
 from the water. The allied kinds, which can not be 
 separated by this simple test, will at once be distin- 
 guished when placed under the microscope by possess- 
 ing no spiral chlorophyll bands as in Spirogyra. When 
 growing vigorously the masses of Spirogyra are an 
 intense light green ; when beginning to fruit they turn 
 brown, and look very uninviting ; but as the characters 
 which distinguish the species are largely drawn from 
 the fruiting condition, the collector soon learns to 
 regard these unsightly objects with favor. 
 
 The vegetative condition may be found at any time 
 during the warmer portion of the year. The fruiting 
 condition occurs from early spring to June and July, 
 and sparingly during the remainder of the warm season. 
 
 The species usually grow intermixed, and almost any 
 
34 COMMON POND SCUM. 
 
 gathering will answer for the present study, as 5. 
 longata Vauch., S. majuscula Kiitz., and similar kinds 
 have been kept in mind as well as 5. quinina in drawing 
 up the outline for laboratory work. 
 
 Spirogyra may be grown in the laboratory, and the 
 vegetative condition kept always at hand, by using a 
 rather deep vessel with opaque sides, and occasionally 
 dropping in a small piece of peat which has been 
 thoroughly boiled and afterward saturated with the 
 following nutritive solution: 1,000 cc. of water, i gm. 
 potassic nitrate, .5 gm. sodic chloride, .5 gm. calcic sul- 
 phate, .5 gm. magnesic sulphate, and .5 gm. finely pul- 
 verized calcic phosphate. 1 The last, for which burned 
 bone may be used, is only sparingly soluble. If run- 
 ning water can be conducted through the jar contain- 
 ing Spirogyra, so that the water in it may be slowly 
 changed, the peat and nutritive solution can be dis- 
 pensed with. The fruiting plant may be preserved 
 in fair condition for study in a fluid of equal parts of 
 glycerine and alcohol. 
 
 The requisites for study are thrifty growing plants ; 
 fruiting plants, fresh if possible ; alcohol ; glycerine ; 
 and iodine. 
 
 LABORATORY WORK. 
 GROSS ANATOMY. 
 
 A. GENERAL CHARACTERS. Notice 
 i. The yellow-green color as seen in mass. 
 
 1 Sachs, Vorlesungen liber Pflanzen-Physiologie, p. 342. 
 
SPIROGYRA QUININA. 35 
 
 2. The slippery feel, when the plant is taken between the 
 fingers. 
 
 Float a small amount of material in water over a white 
 surface, and observe 
 
 3. The fine unbranched filaments of which it is com- 
 posed. 
 
 4. Their uniform diameter. 
 
 5. Their length. 
 
 Place some in alcohol, and after some time notice 
 
 6. The color imparted to the alcohol by the chlorophyll. 
 
 B. Mount a few filaments, and notice the single row of 
 alternating light and dark dots, indicating the single row 
 of cells. This can not be seen in all specimens. 
 
 C. THE FRUITING PLANT. Mount a few filaments 
 from a fruiting mass, having them well separated on the 
 slide, and search for 
 
 i. Paired conjugating filaments, some cells of which are 
 empty, some with dark colored dots, the zygospores, 
 and a few often remaining unchanged from the vege- 
 tative condition. a 
 
 MINUTE ANATOMY. 
 
 A. GENERAL CHARACTERS. Under low power, 
 notice 
 
 i. The indefinite length ; if traced to the end, the fila- 
 ment will probably be found broken. 
 
 5 The presence of small particles of dirt and other debris makes it diffi- 
 cult to distinguish the zygospores and conjugating filaments with cer- 
 tainty, and it is always best to verify the observation with the compound 
 microscope, if possible. 
 
3 6 COMMON POND SCUM. 
 
 2. The uniform diameter. 
 
 3. The cell contents ; colorless, except the conspicuous 
 green chlorophyll bands. 
 
 B. THE INDIVIDUAL FILAMENT. Using a high 
 power, notice 
 
 1. The shape of the cells. 
 
 2. Their relative length and breadth. 
 
 3. 'Thz cell wall : 
 
 a. The lateral walls j parallel and without markings 
 of any sort. 
 
 b. The end walls ; at right angles to the longitudinal 
 axis, and plain (unless slightly nodulated or 
 infolded, which occurs in a few species). 
 
 4. The absence of any visible sheath, although the pres- 
 ence of at least a thin one has been demonstrated by 
 the slippery feel. 
 
 5. The cell contents. 
 
 a. The chlorophyll bands, taking a spiral course from 
 one end of the cell to the other, passing near the 
 periphery. Note 
 i. The number in each cell. 3 
 
 3 'When a cell is crowded with chlorophyll, the following method may 
 be used to advantage in determining the number of bands : count the 
 number appearing to cross the band ab, between the point a, the upper 
 profile view, and the point b, the lower profile view ; this number plus 
 
 one will be the 
 number re- 
 quired. The 
 diagram shows 
 a cell with four 
 bands of chlo- 
 rophyll. From 
 Bot. Gazette, ix., 
 
SPIROGYRA QUININA. 37 
 
 ii. The number of turns of the spiral. 
 
 iii. The surface, the crenulated and wrinkled 
 margin, and the turned up edges of the 
 band forming a more or less flattened Y m 
 optical section. To obtain a complete con- 
 ception of these particulars, first focus upon 
 the peripheral surface of the band, />., upon 
 the upper (outer) surface of the part nearest 
 the eye, then focus upon the axial (inner) 
 surface, and finally examine the profile of the 
 band seen on the right or left of the cell. 
 
 iv. The nodules at varying distances along the 
 median line of the band. Stain with iodine 
 and note 
 a. An outer ring which is more deeply 
 
 colored, starch, 4 and 
 
 ft. A central light spot, pyrenoid. Both are 
 best seen when but faintly colored. 
 
 v. The yellowish brown color finally imparted to 
 the chlorophyll band. 
 
 b. The feeble brownish color given to the remainder 
 oT the contents of the cells, deeper along the 
 periphery. 
 
 Run under glycerine on the same slide, and note 
 
 c. The contraction of the colored protoplasmic part, 
 and its separation from the cell wall. 
 
 d. In unstained cells presenting the least obstruction 
 from the chlorophyll bands, search for a colorless 
 irregular body with radiating arms, near the center 
 of the cell, the nucleus. This is difficult to demon- 
 strate in some species, but easily seen in others. 
 
 4 Unless the plants have been in sunlight the preceding part of the day 
 the test for starch may not be fully successful. 
 
38 COMMON POND SCUM. 
 
 e. The rounded, usually much brighter body im- 
 bedded in the nucleus, and occupying a consid- 
 erable part of it, the nucleolus. 
 
 f. Draw one or more cells showing all parts noticed. 
 
 6. The turgidity of the cells, shown by the considerable 
 convexity of the last end wall of a broken filament, 
 which is repeated in lessening degree by the walls of 
 successive cells until a point is reached where the pres- 
 sure on opposite sides is equal, and the wall remains 
 plane. Illustrate with a sketch. 
 
 C. THE FRUITING PLANT. Under low power, notice 
 
 1. The filaments lying side by side in pairs, held together 
 by conjugating tubes. 
 
 2. The irregular outline of the filaments, caused by the 
 uneven lateral expansion. 
 
 3. The varying character of the contents of the cells : some 
 with distinct bands of chlorophyll ; some with a con- 
 fused green mass ; some with green or brown rounded 
 bodies of definite shape, the zygospores ; some empty. 
 
 Under high power, notice 
 
 4. The general shape of the cells as influenced by the cell 
 contents. 
 
 5. The conjugating tube : note 
 
 a. The enlargement at the middle, where an indenta- 
 tion marks the line of union of the two originally 
 separate portions. 
 
 b. In some cells which have not yet conjugated, a 
 greater or less protuberance on the side next the 
 accompanying filament ; the beginning of a con- 
 jugating tube. 
 
 6. The cell contents. 
 
SPIROGYRA QUIN1NA. 39 
 
 a. By studying various specimens, trace the changes 
 from the vegetative condition, through the several 
 stages of disintegration of the chlorophyll band 
 and contraction of the protoplasm to the forma- 
 tion of a rounded uniformly greenish-brown mass ; 
 noticing at the same time, that this change takes 
 place side by side with the formation of the conju- 
 gating tube. In general all the stages are easily 
 found. 
 
 b. Where the conjugating tube is fully formed, note 
 that one cell is empty, and the connected cell con- 
 tains a single mass, the spore produced by the 
 conjugation. 
 
 7. The mature zygosporc : note 
 
 a. The shape and color. 
 
 b. The contents. 
 
 c. The wall of greater or less thickness, usually 
 resolvable into two or more layers of different 
 colors. 
 
 8. Make drawings to illustrate the parts and changes of 
 the fruiting filaments. 
 
 ANNOTATIONS. 
 
 In the form and manner of growth of Spirogyra, we 
 meet with no features not seen in Oscillaria or Proto- 
 coccus, except the arrangement of the protoplasm and 
 chlorophyll bodies. The filaments are built on the 
 plan of Oscillaria, with the cells larger, and the sheath 
 so much reduced that it can be demonstrated only with 
 difficulty. In some species of the closely related genus 
 Zygnema, however, the sheath is readily discernible. 
 The increase in the number of cells is effected in the 
 
40 COMMON POND SCUM. 
 
 same manner as in Oscillaria, i. e. by the division of 
 the cell into halves by a transverse partition always in the 
 same direction, with subsequent expansion of the new 
 cells. 
 
 The disposition of the protoplasm shows a marked 
 advancement over the lower plants. Instead of being 
 diffused evenly through the cell, it forms a layer lining 
 the cell-wall, known to older botanists as the primor- 
 dial utricle, 6 while it only partly occupies the central 
 portion of the cell. The remaining space is rilled by 
 the cell-sap, which consists of water holding various 
 substances in solution. The nucleus and nucleolus, 
 particularly the latter, are remarkably large. In the 
 chlorophyll band we have a unique feature ; for while 
 it is common to have the chlorophyll separated in well 
 defined bodies, it is only in Spirogyra and its close rela- 
 tives that it assumes such peculiar and beautiful shapes. 
 
 The presence of starch granules in the chlorophyll 
 bodies is a very significant fact in the physiological 
 study of plants. They, or very similar substances, 
 are the first products of assimilation," being the material 
 from which the elaborate frame-work of the plant is 
 eventually constructed. Usually the starch when first 
 formed is scattered irregularly through the chlorophyll 
 bodies ; in Spirogyra, however, the principal part is 
 collected in a layer of granules about definite centers 
 forming hollow spheres. Within these spheres is a 
 highly refractive protoplasmic body, the pyrenoid. 
 
 5 So named by H. v. Mohl, Bot. Zeit, 1844, p. 273 ; The Vegetable 
 Cell, p. 36- 
 
 6 Cf. Sachs , Handbuch d. Exper.-Phys., p. 307 ; Textbook of Botany, 
 2nd Eng. ed., p. 703 ; Bessey, Botany, p. 178. 
 
SPIROGYRA QUININA. 41 
 
 The starch is imbedded in the chlorophyll bodies, and 
 is quite distinct from the pyrenoid, although the con- 
 stancy in the relative position of the two would indi- 
 cate some connecting influence. The pyrenoids have 
 been long known and variously interpreted, 7 but the 
 recent careful studies of Schmitz 8 show that they are 
 quite analogous to nucleoli, especially in chemical 
 constitution and mode of multiplication. They are 
 only found in some of the algae and in a few higher 
 plants. 
 
 It is when we examine the fruiting of Spirogyra, 
 that its great advancement beyond the simple forms 
 of the protophytes becomes apparent. We meet at 
 once with a true sexual process, which although very 
 simple is yet clearly defined and easily traced. This 
 process, as indeed in all other instances however mod- 
 ified, consists essentially of the intimate union of the 
 protoplasm (especially of the nucleus 9 ) of one cell with 
 that of another, which after a longer or shorter period 
 results in the production of a new individual. Usually 
 in higher groups there is a marked difference in size, 
 and we may conclude in other less apparent respects, 
 between the protoplasm which is fertilized, the female 
 element, and the protoplasm which fertilizes it, the 
 male element. In Spirogyra a slight difference between 
 the two elements, especially in size, has been pointed 
 out by DeBary, 10 Wittrock," and more fully by Ben- 
 
 7 Hofmeisterin Die Lehre von der Pfianzenzelle (1867), p. 370, calls 
 them vacuoles. 
 
 8 Die Chromatophoren der Algen (1882), p. 37 etseq. ; Quart. Jour. 
 Micr. Sci. , xxiv, p. 246. 
 
 9 Cf. Strasburger, Neue Untersuchungen, p. 80. 
 10 Untersuchungen Uber die Familie der Conjugaten, 1858, p. 4. 
 "Quart. Jour. Micr. Sci., 1873, p. 123. 
 
42 COMMON POND SCUM. 
 
 nett. 18 According to Bessey," however, we should 
 consider this case the simplest kind of sexuality, in 
 which there is as yet no differentiation into proper 
 male and female. For the further discussion of sexu- 
 ality in plants, the student is referred to the writings 
 of Pringsheim, 14 Sachs," Ward, 16 Strasburger, 17 and 
 others. 
 
 The two plants previously examined may be found 
 in any month of the year, but the one now under 
 examination dies, and entirely disappears from sight 
 by the time winter has fairly set in. It is reproduced 
 the coming spring by the germination of the zygospores, 
 which lie at the bottom of the water during the 
 winter. These resting spores are admirably fitted for 
 spanning this unfavorable season for vegetation. As a 
 rule they require a long period of rest before reaching 
 the germinating condition, so that while they are 
 formed in the earlier part of the warm season, it is 
 usually not till the following spring that they show a 
 disposition to grow ; they are dense and heavy, and 
 therefore sink to the bottom as soon as set free by the 
 decomposition of the filaments in which they grew ; 
 and lastly, their thick double or triple covering serves 
 as an ample protection to the living protoplasm with- 
 in. 
 
 12 Jour. Linn. Soc., xx (1884), p. 430; Amer. Nat., xvii (1884), p. 421. 
 
 13 Amer. Nat., xix (1885), p. 995. 
 
 14 Monatsber. d. k. Akad. der Wiss. in Berlin, 1869. 
 16 Textbook of Botany, 2nd Eng. ed., p. 986. 
 
 16 Quart. Jour. Micr. Sci., 1884, p. 262. 
 " Op. cit. 
 
WHITE RUST. 
 
 Cystopus candidus Lev. 
 
 PRELIMINARY. 
 
 THIS isavery common parasitic fungus, forming white 
 patches on the surface of the leaves, stems and flowers 
 of many cruciferous plants, such as various species of 
 Capsclla, Sisymbrium, Lcpidium, Nasturtium, Sinapis, 
 and Raphanus. It is especially abundant upon Cap- 
 sella or shepherd's purse, 1 from early spring till late 
 in the fall, whitening and distorting the stems, leaves 
 and flowers. Yet, notwithstanding such luxuriant 
 growth, the sexual condition with resting spores is not 
 abundantly found on this host, but is, however, 
 produced in great luxuriance inside the flowers and 
 flowering branches of radish (Raphanus), causing 
 them to become enormously enlarged, sometimes even 
 two to five centimeters (one or two inches) across (see 
 
 fig- 3). 
 
 It is possible, with patience and care, to make out 
 the parts without the use of chlor-iodide of zinc, but it 
 affords so much assistance that it ought to be used if 
 obtainable. 
 
 The requisites for the following study are branches 
 
 1 Fora description of shepherd's purse see p. 222. 
 
44 WHITE RUST. 
 
 of Capsella bearing the rust, dried or fresh ; the same, 
 together with some young terminal portions of affected 
 branches, preserved in alcohol ; the swollen flowers of 
 radish or Capsella taken when not too young, but still 
 tender and brittle, preserved in alcohol ; freshly gath- 
 ered branches of rusted Capsella, or some which have 
 not been gathered more than twenty-four hours and 
 kept in a moist bell jar; chlor-iodide of zinc; potassic 
 hydrate ; and iodine. 
 
 LABORATORY WORK. 
 GROSS ANATOMY. 
 
 1. The vegetative body of the plant consists of delicate 
 transparent threads, ramifying through the tissues of 
 the host on which it grows, and can not be detected 
 without the aid of the compound microscope. 
 
 2. The sort : in a fresh or dried specimen notice 
 
 a. The white blister-like pustules on the surface of 
 the host, son ; shape and extent. 
 
 b. The thin external membrane, at first entire, then 
 becoming ruptured in the middle. 
 
 c. The white powdery spores, conidia, which drop 
 out upon jarring, if the specimen is dry. 
 
 3. Mount a section from an alcoholic specimen of radish 
 flower containing Cystopus, stain with chlor-iodide of 
 zinc, and notice 
 
 a. The numerous dots scattered through the tissue 
 of the radish, the oospores or resting spores. The 
 staining shows them as red dots lying in a blue or 
 yellow ground tissue. 
 
C YS TOP US CA NDID i '.s. 45 
 
 MINUTE ANATOMY. 
 
 Mount a transverse section of an alcoholic specimen of a 
 stem or leaf bearing Cystopus, and under low power 
 notice 
 
 1. A layer of short vertical filaments, conidiophores," 
 together forming the hymenium, which appear to arise 
 from the tissues of the host and bear on their free 
 extremities 
 
 2. Chains of rounded conidia, now mostly detached. 
 
 The vegetative portion of the plant, consisting of branch- 
 ing filaments pervading the tissues of the host, can rarely 
 be made out even after staining, without specially skillful 
 manipulation. 
 
 3. The everted membrane formed from the surface cells of 
 the host, formerly covering the sorus. 
 
 4. Draw. 
 
 Under high power notice 
 
 5. The conidia : exact shape, wall and contents. 
 
 6. The delicate neck or pedicel supporting each conidium 
 before becoming detached. 
 
 7. Draw a conidiophore with its conidia. 
 
 Take a piece of the host bearing conidia and boil for a 
 minute or two in potassic hydrate ; remove a portion to the 
 slide, tease apart thoroughly with needles, and stain with 
 chlor-iodide of zinc. Notice 
 
 8. Much branched, often matted filaments, mycelium, 
 pulled out from the tissues of the host. 
 
 2 Cf . fig. 8. 
 
46 WHITE RUST. 
 
 a. The irregular thickness of the mycelial filaments, 
 or hyphae. 3 
 
 b. The absence of transverse partition walls. 
 
 c. Draw a few hyphae. 
 
 9. The groups of conidiophores. 
 
 a. The manner in which the conidiophores arise 
 from the vegetative hyphae. 
 
 b. The successive degrees of abstriction of the 
 conidiophores resulting in the formation of the 
 spores. 
 
 c. Draw a group of conidiophores with the attached 
 hyphae. 
 
 Prepare a slide as before, using the immature terminal 
 part of the branch bearing the Cystopus, preferably a 
 flowering branch ; search among the untorn tissues of the 
 youngest organs, particularly in the pedicels of the young 
 buds, for the extremities of the advancing hyphae. 4 
 After noting the more direct course of the hyphae, and the 
 fewer branches, observe 
 
 10. Very small globular bodies lying along the side of the 
 hyphae, haustoria or sucking organs. 5 They usually 
 appear brighter than the hyphae, and are quite abund- 
 ant. If the illumination is sufficiently strong, observe 
 
 a. The very delicate stalks by which the haustoria 
 are connected with the hyphae. 
 
 b. Draw some hyphae with haustoria. 
 
 *Hypha is the name applied to a single filament, while mycelium is a col- 
 lective term for a number of hyphae. 
 
 4 If properly stained there will be no difficulty in distinguishing the 
 mycelium from the tissues of the host. 
 
 6 It is difficult to demonstrate these without proper staining. 
 
CY STOP US CANDID US. 47 
 
 Dust some conidia from a fresh growing plant 8 upon a 
 slide and mount with water ; 7 in about an hour, notice 
 
 11. The small protuberance formed on one side of some of 
 the conidia, which opens and permits the escape of 
 the protoplasm in the form of several motile bodies, 
 zoospores, 
 
 a. The shape of the zoospores, and the pair of 
 bright spots in each. 
 
 b. Study the increment. 
 
 c. Notice the pair of delicate vibratile cilia, by 
 means of which the movements are effected. Stain 
 with iodine, and the cilia can be seen more easily. 
 Note their length. 
 
 d. The color imparted to the zoospore and its cilia by 
 the iodine. 
 
 <?. Draw some zoospores, and also one or two conidia 
 which have not discharged zoospores, and one or 
 two empty ones. 
 
 12. The sexual reproduction. Stain a section of an alco- 
 holic specimen of radish flower containing oospores 
 with chlor-iodide of zinc, and notice 
 
 a. The numerous globular bodies, stained wine-red, 
 lying in the tissues of the radish, oogonia. 
 
 b. Accompanying them, and stained the same, smaller 
 rounded bodies, antheridia. 
 
 c. In some of the oogonia, a globular mass of 
 granular protoplasm, not completely filling the 
 oogonium, the oosphere. 
 
 d. A slender tube passing from the antheridium to 
 
 6 The conidia will germinate if sown at any time of day, provided the 
 specimens are fresh, but will do so more readily when sown in the morn- 
 ing from plants which have remained over night under a moist bell jar. 
 
 7 Care must be taken that the water does not evaporate, and to guard 
 against this it is best to use a slide having a shallow cell. 
 
48 WHITE RUST. 
 
 the oosphere, the fertilizing tube ; very difficult 
 to demonstrate. Draw. 
 
 e. In older oogonia, more opaque roughened bodies 
 the oospores, formed from the oospheres. Note 
 i. The flexuous ridges on the exterior, 
 ii. The contents, in spores not too mature. 
 /. Draw some oogonia and accompanying antheridia 
 showing different stages of development of the 
 oosphere and oospore. 
 
 Tease out some tissue containing oospores, which has 
 been boiled in potassic hydrate, stain lightly or not at all, 
 and notice 
 
 g. The manner in which the oogonia and antheridia arise 
 
 from the vegetative hyphae. Draw a few examples. 
 
 //. The rather strong, pointed beak sometimes to be 
 
 seen on one side the antheridium, the fertilizing tube 
 
 which has been pulled out of an.oogonium. Draw. 
 
 ANNOTATIONS. 
 
 In Cystopus we have a much simplified condition of 
 an advanced type of development. The higher devel- 
 opment is shown in its sexual reproductive apparatus, 
 the sexual elements being quite dissimilar in size and 
 in behavior. The larger (female) element, the oogo- 
 nium, receives the protoplasm of the smaller (male) 
 element, the antheridium, the former remaining in a 
 passive state, while the antheridium is the active agent 
 in securing the union. This is the essential plan for 
 all higher plants, as well as for the group to which 
 Cystopus belongs, the Oophyta. 8 The transfer of the 
 
 8 The terms Zygophyta, Oophyta and Carpophyta are used for the 
 three great groups of lower plants, in accordance with the suggestion of 
 Prof. C. E. Bessey in the American Naturalist, xvi (1882), p. 46, 
 and first introduced in his Essentials of Botany, 1884. 
 
CY STOP US CANDID US. 49 
 
 protoplasm by means of a fertilizing tube, and the 
 subsequent formation of a thick-walled resting spore is 
 very similar to what takes place in Spirogyra. In both 
 cases the spore clothes itself with a thin inner wall, 
 very difficult to see clearly, and an outer, thick pro- 
 tective wall. In Cystopus this outer wall is sculptured 
 in a manner characteristic of the species. The oospores 
 thus formed remain over winter ; the tissues in which 
 they lie become disintegrated ; they are distributed by 
 rain' and wind, and finally germinate. 
 
 Next to the mode of sexual reproduction, the most 
 interesting feature about the plant under consideration 
 is its habit of life and the adaptations which have been 
 induced thereby. It is throughout its existence a 
 complete parasite, growing and feeding upon plants of 
 a very high degree of organization. Being no longer 
 required to elaborate food for itself, finding it always 
 at hand and of superior quality, it possesses no chlo- 
 rophyll bodies by which it might assimilate its own 
 food, and is therefore quite colorless. As it grows, 
 it sends its branching filaments ramifying throughout 
 all the softer tissues of the host. They do not 
 penetrate the cells, however, but push about between 
 them, and in order to extract the nourishing fluids 
 readily, especially in the newest portions where rapid 
 growth is taking place, send out sucking tubes or 
 haustoria, which penetrating the adjacent cells expand 
 into minute absorbing bulbs. 
 
 The means of distribution which the plant possesses 
 in its oospores is rather limited, being inferior to that 
 of Spirogyra ; and when once established in a host it 
 is debarred from all further locomotion, such as the 
 
50 WHITE RUST. 
 
 moving water imparts to the spores of Spirogyra. In 
 order to secure certain and extensive distribution, there- 
 fore, and to provide for a succession of crops through the 
 growing season, it produces conidia or summer spores 
 in the greatest profusion, which being light and dry 
 are easily blown about by the wind, and are ready to 
 germinate at once. The thin wall and active pro- 
 toplasm of the conidia, from which they derive this 
 advantage, render them at the same time short lived, 
 so that if a conidium does not find favorable con- 
 ditions for growth within a few hours after reaching 
 maturity, it perishes. The conidia germinate in water, 
 and with best results in a film of water, such as is 
 formed by heavy dew. To still further promote dis- 
 tribution, each conidium breaks up into several active 
 zoospores, which, after moving about for fifteen min- 
 utes or so and finally coming to rest, put out a myce- 
 Hal tube that penetrates the host, and forms a new 
 plant. The zoospores, except in being colorless like 
 the parent, remind us of those of Protococcus, serving 
 the same purpose of distribution and reproduction. 
 
 The absence of septa, except for the separation of 
 the antheridia, oogonia and conidia, making the vege- 
 tative portion a continuous cavity, is a character 
 shared with many other members of theOophyta, both 
 colorless and green forms, and with some of the molds 
 belonging to the Zygophyta. 
 
 The student has doubtless been struck with the 
 rarity of the cases in which he could detect a fertilizing 
 tube, even where the antheridium appeared to lie in 
 the proper plane. There is doubtless a reason for this 
 aside from the mere difficulty of manipulation, which 
 
CYSTOPUS CANDID US. 51 
 
 is to be sought in the nature of the parasitism exhibited 
 by Cystopus. Whatever may be the full significance 
 of sexuality, many facts point to the belief that it is 
 an expedient for the reinvigoration of the exhausted 
 energies of the plant. 9 Cystopus is intimately asso- 
 ciated with a plant immensely above it in the scale of 
 development and of a correspondingly higher poten- 
 tiality. Its vigor is in direct ratio to that of its host, 
 which latter far exceeds the requirements of the simple 
 parasite. The energy which the parasite receives 
 from its host may take the place to some extent of that 
 usually obtained through the sexual process. It there- 
 fore seems justifiable to believe that while the anther- 
 idia are in most cases formed, the fertilizing tube is 
 often either not present or functionless, i. e. that we 
 have the production of oospores without the aid of the 
 male element, a method known as parthenogenesis, 10 a 
 difficult matter to establish by observation. This view 
 is rendered more probable by the fact that it is the 
 customary mode of reproduction in some of the closely 
 allied Saprolegniae " which are mostly parasitic for at 
 least a part of their life upon insects, a still more 
 highly organized food than that obtained by Cystopus 
 and its immediate allies. 
 
 9 Ward, Quart. Jour. Micr. Sci. xxiv, (1884), p. 303; Bot. Gaz. ix, 
 p. 146. 
 
 10 Sachs, Text-book of Botany, 2nd Eng. ed., p. 902 ; Ward, 1. c., p. 
 307. 
 
 11 Pringsheim in Jahrb. f. Wiss. Bot., ix ; DeBary, Beitrage zur 
 Morph. u. Phys. der Pilze, 4te Reihe, p. 73 ; Sachs, 1. c., p. 275. 
 
THE LILAC MILDEW. 
 Microsphcera Friesii Lev. 
 
 PRELIMINARY. 
 
 THE mildew on lilac is extremely common in the 
 United States, making the upper surface of the leaves 
 look white and moldy from midsummer on. The 
 first stage at which the fungus is ready to gather is 
 when it appears powdery, which is usually in June or 
 July, the earlier collections being the best. The next 
 gathering should be made in the early part of Septem- 
 ber, and another just before the leaves fall. As the 
 leaves bearing the fungus are gathered, lay them in a 
 book or plant-press to dry. If it is possible to examine 
 the first stage with fresh material it will prove more 
 satisfactory, but for the remainder dried material will 
 answer quite as well. 
 
 The required material consists of dried lilac leaves 
 bearing the fungus, gathered in midsummer and 
 autumn ; and potassic hydrate. 
 
 LABORATORY WORK. 
 
 GROSS ANATOMY. 
 
 A. GENERAL CHARACTERS. Notice 
 
 i. The distribution of the fungus over the surface of the 
 leaf. 
 
MICROSPH&RA FRIESII. 53 
 
 2. The color. 
 
 B. THE CONIDIA. Notice 
 
 i. The pulverulent appearance on the leaves first gathered, 
 caused by the abundant conidia. 
 
 C. THE FRUIT. Notice 
 
 1. The black dots on leaves gathered later in the season, 
 the spore-fruits or perithecia. 
 
 2. Associated with the black dots, other yellow ones, the 
 immature fruits. 
 
 MINUTE ANATOMY. 
 
 A. THE MYCELIUM. Scrape the fungus from the sur- 
 face of a leaf gathered in early summer, having first 
 moistened it with potassic hydrate if the specimen is a 
 dried one, and under high power notice 
 
 1. The colorless filaments of the mycelium. 
 
 a. The branching. 
 
 b. The irregular diameter. 
 
 c. The rarity of partition walls. 
 
 2. Small lateral expansions of the filaments, haustoria, 
 somewhat like irregularly indented disks with very 
 short thick stalks. Generally difficult to find. 
 
 3. Draw. 
 
 B. THE CONIDIA. Prepare a slide as before from a pul- 
 verulent surface, and notice 
 
 1. The abundant conidia, separated and free, owing to the 
 manipulation. 
 
 a. Their shape and color. 
 
 b. The cell-wall and contents. 
 
 2. The conidia-beartng branches, or conidiophores, which 
 leave the mycelial filaments at right angles, and are 
 provided with cross partitions at regular intervals, and 
 
54 LTLAC MTLDP.W. 
 
 to which may yet be attached some fully formed 
 spores. 
 
 3. Draw some conidiophores and conidia. 
 
 C. THE PERITHECIA. Prepare a slide as before with 
 mature fruit, and notice 
 
 1. The shape and color. 
 
 2. The reticulations of the surface due to the cellular 
 structure. 
 
 3. The appendages extending out from the sides. Note 
 
 a. The number. 
 
 b. The color. 
 
 c. The length compared with the diameter of the 
 perithecium. 
 
 d. The cross partitions, if any. 
 
 e. The manner of branching, and the number of times 
 in each. 
 
 4. Draw a perithecium with its appendages. 
 
 Crush the perithecia while watching them through the 
 instrument, by pressing on the cover-glass with a dis- 
 secting needle, and notice 
 
 5. The escape of sacs containing spores, asci. Note 
 
 a. The number from each perithecium. 
 
 b. The general shape. 
 
 c. The short pedicel or beak by which they were 
 attached. 
 
 d. The thin part of the wall at the apex, not to be 
 seen in every case. 
 
 e. The number of spores (ascospores) in each ; their 
 shape. 
 
 /. Draw an ascus with its spores. 
 
MICROSPHMRA FRIESII. 55 
 
 6. Examine younger and younger perithecia to as early a 
 stage as possible. Draw. 
 
 D. The very simple ORGANS OF FERTILIZATION, 
 
 the beginning of the perithecia, can rarely be found 1 ; if 
 seen, notice 
 
 a. The larger axial cell, the carpogonium. 
 
 b. The smaller lateral cell, applied closely to the car- 
 pogonium, the antheridium. 
 
 ^. Draw. 
 
 ANNOTATIONS. 
 
 The group of Carpophyta to which Microsphaera 
 belongs, a very large one, is characterized by having a 
 special covering for the spores, developed as a result of 
 fertilization. Except in some of the higher forms, the 
 fertilization takes place much as in the Oophyta, but the 
 subsequent development is very different, for an out- 
 growth of branches from the portion immediately 
 below the organs of fertilization at once arises which 
 eventually envelops the forming spores and develops 
 into the body of the fruit. 
 
 It is altogether likely that Microsphaera has reached 
 an advanced parthenogenetic stage, i. e. the fruits are 
 largely produced without the transfer of protoplasm 
 from the antheridium to the carpogonium, which consti- 
 tutes fertilization. On this account some other plants 
 better illustrate the fertilization and the early growth of 
 the fruits than the one used ; the student is advised 
 to examine these features, if possible, in Nemalion, one 
 
 1 To get some idea of their shape, examine figs. 188 and 189 in Bessey's 
 Botany, p. 280-1. 
 
5 6 LI LA C MILDE W. 
 
 of the marine algae, or Batrachospermum, one of the 
 fresh-water algae. 
 
 The comparison of Microsphaera with Cystopus is 
 very instructive in showing how practically the same 
 ends have been reached by widely different plants. 
 Both are parasitic, the one living inside the host, the 
 other upon its surface, both deriving nourishment by 
 means of haustoria, in addition to what is absorbed 
 directly through the walls of the filaments. It is some- 
 what doubtful, however, if the haustoria of Micro- 
 sphaera pierce the cells of its host, although those of 
 some closely related species are thought to do so. 2 
 Both bear aerial asexual spores, which are formed 
 by successive abstrictions from vertical mycelial 
 threads, the main difference being that in Cys- 
 topus these must break through the surface tis- 
 sue of the host, and are therefore required to grow in 
 groups in order to exert the necessary force, while in 
 the superficial Microsphaera they are single, and evenly 
 distributed. The conidia of Cystopus germinate by 
 formation of zoospores, while those of Microsphaera 
 grow a mycelial filament at once, a difference due to 
 some obscure cause. Both plants form resting spores, 
 but in Cystopus the protective covering is the thick- 
 ened wall of the spore, in Microsphaera it is a specially 
 developed shell, inclosing a number of spores in sacs. 
 
 There is not much known of the manner in which 
 these fruits pass the winter and give rise in the spring 
 to another growth of mildew. 3 It is plain f-om 
 
 3 Cf. Bessey, Botany, p. 279. 
 
 3 Wolff has studied the germination of the ascospores in Erysiphe. 
 graminis. Bot. Zeit. 1874, p. 183, 
 
MICROSPH&RA FRIESII. 57 
 
 the structure, however, that the spores escape from the 
 sacs through the thin spot at their apex, but not so 
 evident how they escape from the shell of the fruit 
 and reach the host plant. The appendages we 
 may suppose are of some service in distributing the 
 fruits. 
 
COMMON LIVERWORT. 
 Marchantia polymorpha L. 
 
 PRELIMINARY. 
 
 THIS plant is common throughout America and 
 Europe. It grows among grass, over wet soil or 
 rocks, in dryer spots along walls and fences, and occa- 
 sionally in more exposed situations, but is most luxu- 
 riant in damp shady places. The vegetative part con- 
 sists of flat, green, leaf-like stems, twelve millimeters 
 (half inch) or so wide and five to eight centimeters 
 (two or three inches) long, appressed to the ground, 
 held down by numerous silky hairs on the under side, 
 and much branched, usually forming extended mats. 
 
 There are two sorts of reproductive branches which 
 occur on separate plants. These branches (see fig. 2) 
 are slender stalks about an inch high, bearing flat disk- 
 like heads a quarter of an inch or more across the 
 male with scallops, the female with finger-shaped rays. 
 The two forms sometimes grow at the same spot or 
 locality, but quite as often entirely apart from each 
 other. Besides these organs there are often small 
 sessile cups (cupules) on the upper surface of the stems, 
 containing green grains. 
 
 If either cupules or reproductive branches are present, 
 
MARCHANTIA POL YMORPHA. 59 
 
 no other plant is likely to be mistaken for it. In their 
 absence it may be told from any of the lichens by the 
 small, diamond-shaped markings on its upper surface. 
 A common liverwort growing in damp places (Conoceph- 
 alns conicus) may be known in its sterile condition by 
 its larger size, larger areolae and more prominent sto- 
 mata which in Marchantia are barely visible to the 
 naked eye, but in Conocephalus are as large as pinholes. 
 A common greenhouse liverwort of similar appearance 
 (Lunularia crnciatd] may be distinguished by its cres- 
 cent-shaped cupules, lacking a border on one side. 
 
 Marchantia grows luxuriantly in the greenhouse, 
 producing an abundance of cupules, and often fruit- 
 ing. It maybe placed on the pots in which other plants 
 are grown or given a bed to itself. 
 
 When gathering material, care should be taken to 
 save fertile plants with young heads ; in female plants, 
 especially, some heads should be no larger than a quar- 
 ter the size of a pinhead, and which at this stage of 
 growth are to be detected in the sinus at the growing 
 end of the stem. 
 
 To complete the laboratory work requires fresh or 
 alcoholic specimens bearing cupules and both kinds of 
 reproductive branches ; fresh specimens of the male and 
 female heads ; and iodine. 
 
 LABORATORY WORK. 
 GROSS ANATOMY. 
 
 A. GENERAL CHARACTERS. Note 
 i. The flattened horizontal stem or thallus, composing 
 the larger part of the plant. 
 
60 COMMON LI VER WOR T. 
 
 a. The branches ; all lying in the same plane as the 
 main axis, except 
 
 b. The fruiting branches, consisting of erect stalks, 
 pedicels, supporting disk-like heads or receptacles 
 of two sorts, to be found on separate plants : 
 
 i. The antheridial (sterile) with scalloped heads, 
 
 and 
 ii. The archegonial (fertile) with star - shaped 
 
 heads. 
 
 2. The numerous hairs on the under surface of the thallus. 
 
 3. The dark brown or purple leaves, somewhat concealed 
 by the hairs, and closely overlapping to form a low 
 ridge along the median line beneath. 
 
 4. The scales along the sides of the thallus beneath, 
 some projecting beyond the margin ; more conspicu- 
 ous on plants grown in damp shady places. 
 
 5. Sessile cups or cupules (very prominent when present), 
 seated on the upper surface of the thallus, containing 
 bright green flat bodies, the gemmae. 
 
 B. THE STEM. Note 
 
 1. The color of the upper and lower surfaces in fresh 
 specimens. 
 
 2. The well marked median line, midrib ; and the broad 
 expansions, wings, on either side of it. 
 
 3. The indented apex. 
 
 4. Mode of branching, dichotomous ; each stem is resolved 
 into two equally diverging stems, one of which soon 
 exceeds the other by more rapid growth, giving the 
 false appearance of being monopodial. 
 
 5. On the upper surface the small areas, areolae, best 
 seen on the older parts, in the center of each of which is 
 
MARCIfANTIA POLYMORPHA. 6 1 
 
 a. A circular breathing-pore, or stoma, readily de- 
 tected with the lens. 1 
 
 6. On the under surface, notice the absence of stomata 
 and areohi3. 
 
 7. Make an outline sketch of a branching stem to show 
 the contour, the median line, and the mode of branch- 
 ing. 
 
 8. Mount a transverse section, and if from a growing 
 plant, notice the pale middle tissue, the green upper 
 surface, the dark-colored lower surface, and the group 
 of median leaves projecting downward from the mid- 
 rib ; if from an alcoholic specimen the color is wanting. 
 If the specimen is very thin and carefully prepared, 
 long narrow air-cavities may be seen just beneath the 
 upper surface with possibly stomata leading out from the 
 center of some. 
 
 C. THE LEAF. Remove the hairs from the lower sur- 
 face of the stem, and notice 
 
 1. The direction and manner of the overlapping of the 
 
 leaves. 
 
 2. The shape. 
 
 3. The curvature and extent of the line of insertion. 
 
 4. Illustrate shape, and position on the stem by diagrams. 
 
 D. THE TRICHOMES. These are of two kinds, the 
 hairs and the scales. 
 
 i. The hairs. Notice 
 
 a. The silky mass extending downward along the 
 midrib, serving for roots, rhizoids : the part of the 
 thallus from which they arise. 
 
 1 The areolne and stomata are very large in Conocephalus conictis, the 
 latter being plainly seen without the aid of a lens. 
 
6 2 COMMON LIVER WOR T. 
 
 b. The closely appressed strengthening hairs on the 
 wings ; their origin and direction of growth. 
 
 2. The scales. Notice 
 
 a. The slightly projecting marginal scales, along the 
 under edge of the thallus ; insertion and direc- 
 tion. 
 
 b. The colorless intermediate scales, midway between 
 the edge and the midrib ; insertion and direction. 
 
 Mount both kinds of scales and notice 
 
 c. The shape of each. Draw. 
 
 E. THE CUPULE. Note 
 
 1. Position on the stem. 
 
 2. Shape and size. 
 
 3. The degree of smoothness of the outer and inner sur- 
 faces. 
 
 4. The thin margin, infolded when young ; shape and 
 regularity of the teeth. 
 
 5. The gemma within ; remove some and place on a 
 white surface, and note their form usually two 
 notches can be detected opposite each other. 
 
 6. Draw a cupule with its gemmae. 
 
 F. THE FRUITING BRANCHES. 
 
 1. Position on the stem ; note that they are always con- 
 tinuations of the midrib, and consequently apical, 
 although sometimes, by the prolongation of the wings, 
 appearing to rise from the upper surface. 
 
 2 . The pedicel ; notice 
 
 a. Color and striation. 
 
MARCHANTIA POLYMORPHA. 63 
 
 b. The flat, green, posterior* surface of the arche- 
 gonial branch, wanting in the antheridial. 
 
 c. Pull a pedicel in two and notice the hairs pro- 
 jecting from a pair of grooves on its anterior 
 face. 
 
 d. Make a transverse section of the antheridial ped- 
 icel and notice the outline, and the position 
 and form of the grooves. Draw. 
 
 e. In a similar section of the archegonial pedicel 
 notice the outline, grooves, and the posterior 
 chlorophyll-bearing portion, with its row of air 
 cavities. Draw. 
 
 The head of the antheridial branch, consisting of a 
 large receptacle and minute and inconspicuous anther- 
 idia imbedded in it ; notice 
 
 a. The general shape of the receptacle. 
 
 b. The particular outline of the margin. 
 
 c. The broad radiating ridges on the upper and 
 
 lower surfaces. 
 
 d. The narrow wing-like margin, more easily dis- 
 tinguished by holding the head toward the light. 
 
 f. The numerous scales on the ridges beneath, most 
 abundant toward the margin. 
 
 /. Cut a vertical section and observe the rather 
 large oval cavities beneath the ridges ; each cav- 
 ity contains a single sac, antheridium, holding 
 the innumerable fertilizing bodies, antherozoids, 3 
 neither distinctly visible. If the antheridium is still 
 
 8 1. e., the surface looking away from the axis of the stem and corre- 
 sponding to its upper surface. 
 
 3 The antherozoids are far too small to be seen except with a compound 
 microscope ; they escape through openings in the upper surface, also too 
 small to be made out in this connection. 
 
64 COMMON LI VER IVOR T. 
 
 distended with antherozoids, it will completely 
 fill the cavity and appear as a darker or lighter 
 spot in the tissues, according to the thickness of 
 the section, but if the antherozoids have escaped, 
 the collapsed antheridium remains, although it can 
 rarely be detected, and the cavity appears empty. 
 The antherozoids may sometimes be seen in 
 mass as a faint cloud escaping into the water of 
 the slide, especially when pressure is applied to 
 the cover-glass. 
 
 g. Make a horizontal section from the upper part of 
 the head, after first removing a thin surface slice, 
 and again observe the cavities. 
 
 h. Draw an uninjured antheridial branch, giving 
 prominence to the upper surface of the head. 
 
 4. The head of the archegonial branch, consisting of a star- 
 shaped receptacle and circle of reproductive organs 
 beneath ; notice 
 a. The receptacle ; its general shape. 
 
 i. The rays, with a longitudinal crease beneath ; 
 
 their number, 
 ii. The cleft, which extends to the posterior side 
 
 of the pedicel. 
 />. The reproductive organs forming groups alternating 
 
 with the rays. 
 
 c. Carefully separate one of the groups with a needle, 
 without detaching it, and notice 
 i. The border, perichsetium, surrounding it, and 
 
 inclosing 
 
 ii. The several young sporogonia. With a needle 
 remove the sporogonia to a slide without injur- 
 ing the perichsetium. Now observe that 
 iii. The two halves of the perichaetium are united 
 
MARCHANTIA POLYMORPHA. 65 
 
 at an acute angle next the pedicel, and by an 
 
 infolded flap next the edge of the receptacle. 
 
 This flap is best seen by spreading apart the 
 
 rays between which the perichaetium is 
 
 situated, 
 iv. Remove the perichaetium and spread out on 
 
 the slide with the sporogonia already placed 
 
 there ; notice 
 
 a. The fimbriated free edge of fatperichatium. 
 
 /3. The opaque sporogonia with their very short 
 thick stalks, each inclosed by a delicate 
 sheath, the perianth, twice the length of 
 the immature sporogonia, but equaling 
 or even shorter than the older ones. 
 Draw. 
 
 v. Tear away the perianth and notice that it is 
 quite free from the sporogonium, which, with 
 its stalk, can now be seen more clearly. Draw. 
 
 d. In a head from a fresh specimen 4 having mature 
 sporogonia protruding from the perichaetia, notice 
 
 i. The /<?;/ of the sporogonia. 
 
 ii. The contents ; a fluffy yellow mass when 
 
 escaping from a freshly ruptured fruit, 
 iii. Mount and notice the dust-like part, spores, 
 
 and the short delicate hairs, elaters. 
 iv. Breathe gently upon a mass of dry elaters and 
 
 notice the movement caused by the moisture 
 
 of the breath. 
 
 e. Draw an uninjured archegonial branch, giving 
 
 prominence to the under surface of the head. 
 
 4 An alcoholic specimen does as well, except to illustrate ii and iv 
 infra. 
 
66 COMMON LIVERWORT. 
 
 MINUTE ANATOMY. 
 
 A. THE TRICHOMES. Remove some of the hairs 
 that are pressed tightly upon the under surface of the 
 wings of the stem, and under high power notice 
 
 1. The shape. 
 
 2. The internal projections i sometimes horn-like, branched, 
 and extending quite across the cavity of the hair. 
 
 3. The more or less prominent spiral constriction on which 
 the projections are seated, giving the walls in optical 
 section the appearance of alternate scallops. 
 
 4. Draw. 
 
 5. Compare the loose silky hairs along the middle of the 
 stem, the true rhizoids, with the preceding. Draw. 
 
 Mount marginal and intermediate scales, and notice 
 
 6. The cellular structure of each. Draw. 
 
 B. THE STEM OR THALLUS. Remove a thin slice 
 from the upper surface of the stem, mount with the free 
 surface uppermost, and under high power notice 
 
 1. The surface or epidermal cells; their shape and con- 
 tents. 
 
 2. The large breathing pores or stomata, encircled by 
 rows of special cells, the supplementary guard-cells ; 
 number of cells in each circle. 
 
 3. Draw a stoma with some surrounding tissue. 
 Remove the cover-glass, remount the section with the 
 
 free surface downward, and disregarding other features, 
 notice 
 
 4. The four innermost (now lying uppermost) cells of the 
 stomata, having more or less prominent projections 
 (sometimes obsolete) arching over toward the center 
 of the pore, the true or active guard-cells. Draw. 
 
MARCHANTIA POLYMORPHA. 67 
 
 Take a very thin slice in the same way from the lower 
 surface, and notice 
 
 5. The shape of the cells of the epidermis, absence of 
 stomata, and the insertion of the hairs. Draw. 
 
 Make a vertical section of the stem parallel to the 
 direction of the radiating tissues of the wings, which is 
 usually at about an angle of forty-five degrees to the line 
 of the midrib ; notice 
 
 6. The wider colorless under part of the stem. 
 
 7. The narrower chlorophyll -bearing upper part. 
 In the colorless portion of the stem, notice 
 
 8. The closely packed parenchyma cells, bordered on 
 one side by the marginal row of cells forming the 
 lower epidermis. 
 
 9. The shape of the parenchyma cells, their uniformity 
 of size, and the transverse reticulated thickenings. 
 
 10. The smaller size of the epidermal cells, forming an 
 indefinite marginal row, the walls plain, and either 
 colorless, purple or brown. 
 
 11. Draw several cells of the lower epidermis, and some 
 of the adjacent parenchyma. 
 
 In the upper green layer of the stem, notice 
 
 12. The large air cavities, from the bottom of which a 
 thick growth of (in fresh specimens very green) cells 
 arises, branching in a cactus-like manner. 
 
 13. Note the shape of these cells, their manner of union, 
 and the rounded (in fresh specimens bright green) 
 chlorophyll grains. Draw. 
 
 In the same section, if sufficiently thin and perfect, ex- 
 amine 
 
 14. "^^ partition wall which separates contiguous cavities, 
 
6 8 COMMON LI VER WOR T. 
 
 and the over-arching roof formed of the single epider- 
 mal layer of cells. Draw. 
 
 When a section is found which has passed through a 
 stoma, notice 
 
 15. The chimney-like structure, the number of cells in 
 depth, and the shape of the cut ends of the cells, es- 
 pecially of the outer and innermost ones. Draw. 
 
 16. Illustrate the structure of the stem as shown in the 
 longitudinal section by a diagram. 
 
 17. Cut a vertical section of the wing at right angles to the 
 longitudinal one already examined, and compare with 
 it : especially note the difference in the outline of the 
 parenchyma cells, and the frequent absence of reticu- 
 lated markings. Draw. 
 
 C. THE LEAF. Remove a leaf from the stem, best 
 taken from a young stem where the leaves are comparatively 
 large and conspicuous, and notice 
 
 1. The shape of the cells, absence of markings and of 
 chlorophyll, and the uniformity of the cells throughout 
 the leaf. Draw. 
 
 Make a transverse section of the stem at right angles to 
 the midrib, and a good transverse section of the leaves will 
 usually be obtained : notice 
 
 2. The single row of cells forming the blade, or some- 
 times two or three rows at the base, and the manner in 
 which the older leaves over-arch the younger. Draw. 
 
 D. THE CUPULE. Remove a cupule and place face 
 upward on the slide, ignoring for the present the gemmae 
 which float out from it ; press the cover-glass down until the 
 cupule is sufficiently flattened ojit, when it will appear as a 
 wide ring of tissue, the bottom of the cup having been cut 
 away. Examine with low power 
 
MARCHANTIA POLYMORPHA. 69 
 
 1. The border of triangular teeth ; the fimbriated sides 
 and elongated apex of each tooth. The inner part of 
 the cupule is too thick to be seen well. 
 
 Place under a higher power. 
 
 2. Examine the structure of the/^/Aand their marginal hairs 
 more carefully, and draw. Vary the focus, and notice 
 whether the inner surface of the cup is smooth or rough. 
 
 Remove the cover-glass, turn the specimen over, and ex- 
 amine as before. Notice that 
 
 3. The outer surface of the cup is covered with short hairs 
 vi papilla. 
 
 Make a vertical section passing through the center of a 
 cupule and through the stem on which it is seated, examine 
 under low power, and note 
 
 4. The two parts of the cupule. 
 
 a. The base. 
 
 b. The abruptly spreading limb. 
 
 c. Arising from the bottom of the cup, flattened tri- 
 chomes, the genuine , in various stages of develop- 
 ment. 
 
 d. Illustrate with diagram. 
 
 Examine the limb under high power, noting 
 
 5. The small cells of the inner epidermis, the parenchy- 
 matous tissue beneath, the absence of a distinctly 
 marked outer epidermis, and the short one- or two- 
 celled hairs on the outer surface. Draw. 
 
 6. Examine next the base of the cupule, noting the man- 
 ner in which the layer of air cavities of the stem and 
 their chlorophyll tissue is continued up the outside of 
 the cup as far as the insertion of the limb. 
 
 7. Upon the inside of the cup, observe 
 
 a. The numerous glandular, one-celled hairs, and 
 among them 
 
7 COMMON LI VER IVOR T. 
 
 b. Thicker hairs in various stages of cell-multiplica- 
 tion, from the first division into two cells by a 
 transverse wall, to the fully formed many-celled 
 gemma still attached by \\spedicel. 
 
 c. Draw part of the bottom of the cup, to show inser- 
 tion and form of the glandular hairs and young 
 gemmae. 
 
 8. Examine under a low power the mature gemmce which 
 have floated from the cupule, and note 
 
 a. The shape. 
 
 b. The cellular structure. 
 
 c. Cells here and there devoid of chlorophyll. 
 
 d. The scar left by the pedicel. 
 
 e. The pair of vegetative notches placed midway, 
 one on the right, the other on the left side, in 
 which, when the gemmae are sufficiently mature, may 
 be seen 
 
 /. The early stage of the new plantlets in form of 
 
 delicate papillae. 
 g. Draw. 
 E. THE ANTHERIDIAL BRANCH. 
 
 i. The pedicel. Pull in two a pedicel and remove some of 
 the hairs which protrude from two grooves on its pos- 
 terior face, and lay upon a slide. Now make a trans- 
 verse section of the pedicel and mount with the hairs. 
 Under low power, notice 
 
 a. The general outline of the section, the two con- 
 spicuous grooves or channels, and the uniformity of 
 the whole tissue. Illustrate with diagram. 
 
 Under high power, notice 
 
 b. The colorless dense parenchyma forming the mass 
 of the pedicel, bounded by the surface row of small 
 
MARCHANTIA POL YMORPHA. 1 1 
 
 epidermal cells, in fresh specimens usually colored 
 purple or brown. Draw. 
 
 c. The overlapping projections inclosing the right 
 and left channels or grooves, from the apex and 
 sides of which arise leaves, which seen in cross- 
 section appear as a single row of cells, or double 
 rowed at the base ; observe the manner of infold- 
 ing, comparing sections when convenient from 
 different parts of the same pedicel, and from 
 different pedicels, drawing the most interesting. 
 
 J. In some of the grooves will be found excellent 
 cross-sections of the hairs. Examine now the hairs 
 pulled from the grooves. Draw. 
 
 e. Remove a thin paring from the anterior surface of 
 
 the pedicel, examine the epidermal cells, and, by 
 
 varying the focus, the face of the leaves. Draw 
 
 a few cells of each. 
 
 2. The receptacle. Take a slice from the ridges on the 
 
 upper surface of the receptacle, mount with the free 
 
 surface uppermost, and notice 
 
 a. The stomata and epidermal cells. 
 
 />. The flares, around which the epidermal cells con- 
 verge, the mouths to the underlying cavities con- 
 taining the antheridia. 
 
 c. Draw. 
 
 Remount the section with the free surface downward, 
 focus on the cut surface, and in the thicker part of the 
 section notice 
 
 d. The large air cavities, producing from the sides 
 branched chlorophyll filaments like those of the 
 stem. Focus deeper into the cavities and notice 
 The stomata, the four innermost cells inflated and 
 almost or quite closing the pore of the stoma. 
 
 /. The pores of the antheridial cavities situated in 
 
7 2 COMMON LI VER IVOR T. 
 
 the walls between the air cavities; also the disposi- 
 tion of the surrounding tissue. 
 
 Cut a rather thick vertical section a little to one side 
 of the center of an immature receptacle, and notice 
 
 g. The chlorophyll cavities,with their chlorophyll cells. 
 
 h. The much larger antheridial cavities, which are 
 
 quite likely to be empty, or may contain the 
 
 membranous remains of the antheridial sac, or may 
 
 be more or less filled with 
 
 3. The antheridium with its paraphyses j notice 
 
 a. The shape of the antheridium. 
 
 b. The pedicel by which it is attached to the bot- 
 tom of the cavity. 
 
 c. The structure of the wall, brought into view by 
 focusing on the part nearest the eye. 
 
 d. The wall as seen in optical section, only a single 
 cell in thickness. 
 
 e. The uniform contents, consisting of very small 
 squarish cells, filled with colorless protoplasm. 
 
 /. The several unicellular paraphyses surrounding 
 the base of the antheridium, and not much longer 
 than its pedicel ; best seen when the antheridia are 
 young. 
 
 g. That the antheridia are younger toward the margin 
 of the head, and older toward the center. 
 
 h. Draw an antheridium with its paraphyses. 
 
 4. The antherozoids ; if the section just examined be from 
 a freshly gathered specimen, the contents of many of 
 the antheridial cells will have escaped into the water of 
 the slide 6 ; notice 
 
 5 An excellent way to obtain antherozoids for examination is to place 
 a small drop of water on a slide and hold a freshly gathered head in it for 
 a few moments, when, if the antherozoids are ripe and abundant, they 
 will make the water milky. 
 
MARCHANTIA POLYMORPHA. 73 
 
 a. The rapid motion of the antherozoids, becoming 
 slower and slower until after some time they come 
 quite to rest. 
 
 b. Their form a slender filament, at the anterior end 
 of which may be detected,when the motion becomes 
 sufficiently slow, 
 
 c. Two very delicate vibratile cilia; the form and 
 motion may be more readily studied by staining 
 with iodine, and watching the antherozoids as they 
 pass gradually under its influence. 
 
 d. The delicate hyaline vesicle and its contents, 
 dragged about by some of the antherozoids 
 until finally detached. 
 
 If the section be from an alcoholic specimen, some an- 
 therozoids will have escaped, or can be made to escape by 
 pressing on the cover-glass, when the form can be studied 
 as before, but the filaments will be found quite closely 
 coiled, the cilia difficult to detect, and the vesicle probably 
 invisible. 
 
 F. THE ARCHEGONIAL BRANCH. 
 
 i. The pedicel ; in a transverse section under low 
 power, notice 
 
 a. The general outline. 
 
 b. The two grooves. 
 
 c. The posterior plate containing air cavities and 
 chlorophyll tissue. 
 
 d. Illustrate with diagram. 
 Under high power, notice 
 
 e. The larger rounded anterior part, in every essential 
 like that of the antheridial pedicel. 
 
 /. The smaller flattened posterior part in which lie 
 i. The air cavities, like those of the thallus, ex- 
 cept smaller, sparsely provided with 
 
74 COMMON LI VER WOR T. 
 
 ii. Chlorophyll-bearing filaments ; springing indif- 
 ferently from the floor or walls, 
 iii. The (usually single) layer of small cells form- 
 ing the floor, partition walls, and roof of the 
 cavities. 
 
 iv. The stomata, these will occasionally be cut 
 across ; note the number of cells in depth, 
 and their relative size. 
 v. Make a drawing to illustrate the several 
 
 points. 
 
 Make a longitudinal antero-posterior section and note 
 g. The length of the parenchyma cells, and shape of 
 
 the air cavities. 
 
 h. Remove a thin paring from the flat posterior 
 surface of the pedicel, and mount with the free 
 surface uppermost, noticing the epidermal cells and 
 stomata. Draw. 
 
 i. Remount the section with the free surface down- 
 ward ; note the relative size of the air cavities, 
 and the appearance of the stomata. 
 
 Cut off a pedicel near the base, make an antero-posterior 
 longitudinal section of the basal portion, together with the 
 stem from which it arises, and note 
 
 j. The continuity of the tissues of the pedicel with 
 
 those of the stem. 
 
 Cut off a pedicel near the head, make an antero-posterior 
 longitudinal section passing through the pedicel and through 
 the cleft in the receptacle, and note 
 
 k. The continuity of the tissues of the pedicel with 
 
 those of the receptacle. 
 
 2. The receptacle ; cut a transverse section of one of 
 the rays, and notice 
 
 a. The central cavity in which lie numerous hairs 
 like those in the grooves of the pedicel. 
 
MARCHANTIA POLYMORPHA. 75 
 
 b. The encircling tissues, indented at one point, yet 
 continuous ; notice further 
 
 The internal portion of uniform parenchyma. 
 The external row of air cavities, containing 
 chlorophyll-bearing filaments, and provided 
 with stomata, essentially like those of the 
 pedicel, 
 iii. Papillary trichomes arising from many of the 
 
 epidermal cells. 
 
 Using an immature branch, cut a transverse section 
 across two or three rays nearer the center of the head and 
 passing through the groups of sporogonia, notice 
 
 c. The central cavity, much smaller than in the rays. 
 
 d. The right and left sides, which instead of being 
 united, are prolonged into the perich&tium, so 
 that the perichaetial leaf on the right side of the 
 group of sporogonia belongs to the left side of 
 the right hand ray, while the perichaetial leaf on 
 the left side belongs to the right side of the left 
 hand ray. 
 
 e. The section of the perichaetial leaves, one cell in 
 thickness, or sometimes two at the base. 
 
 /. Examine the flat surface of the perichaetium, the 
 shape of the cells, and the notched and fimbriated 
 margin. Draw. 
 
 g. The bent filaments, paraphyses, composed either 
 of a single row of cells, or of two or more 
 united rows for part or the whole length. 
 Draw. 
 
 3. The archegonia, 6 the flask-shaped bodies among the 
 paraphyses, consisting of 
 
 6 Bear in mind that the archegonia are called sporogonia after fertiliza- 
 tion and a certain amount of growth has taken place. 
 
76 COMMON LIVER IVOR T. 
 
 a. The bulbous base : in optical section make out a 
 single layer of cells inclosing a central cavity. 
 
 b. The long neck} 
 
 c. A ring rising up around the base in some cases, 
 the early stage of the perianth. 
 
 d. Draw. 
 
 4. The sporogonia ; selecting the immature ones, notice 
 under a low power 
 
 a. The perianth ; its deeply notched margin, which 
 is usually twisted over the fruit ; observe the 
 cellular structure. Draw. 
 
 b. Tear away the perianth, examine the surface of 
 the sporogonium and its stalk, and notice the 
 remains of the neck of the archegonium. 
 
 c. Crush some of the sporogonia by pressing upon 
 the cover-glass, noticing the escaping contents 
 consisting of slender threads having granular 
 protoplasm and pointed ends, the immature elaters, 
 and rows of young spores, both radiating from the 
 base of the fruit. Draw. 
 
 d. Examine some mature spores ; notice 
 i. The wall. 
 
 ii. The contents. 
 
 e. Examine the mature elaters ; notice 
 
 i. The delicate wall, not easily distinguished. 
 
 ii. The spiral bands* 
 
 iii. Examine some dry elaters without a cover- 
 glass, and observe the movements when damp- 
 ened by the breath. 
 
 7 These archegonia, unless taken from a very young head, are mostly 
 sterile, not having been fertilized, as shown by the shriveled neck, and 
 the absence of a well defined protoplasmic mass in the basal cavity. 
 
 8 Their number can be ascertained by the method used for Spirogyra, 
 P. 36. 
 
MARCHAXTIA POLYMORPHA. 77 
 
 Section or crush a young archegonial hc-.iJ. not exceed- 
 ing a pinhead in size, and giving attention only to the 
 archegonia, notice 
 a. The single layer of cells forming the wall of the 
 
 bulbous part, passing into 
 It. The few rows of cells forming the neck, appearing 
 
 in optical section like two rows, ending above in 
 
 c. The stigmatic cells, which are spread apart at the 
 time of fertilization. 
 
 d. The well denned carify in the bulbous part, con- 
 taining (if not yet fertilized) 
 
 e. The globular oosphere. 
 
 /. The narrow canal extending the length of the 
 neck, through which the antherozoids reach the 
 oosphere to fertilize it. 
 
 ANNOTATIONS. 
 
 In a morphological point of view Marchantia is a 
 plant of unusual interest, on account of its remarkable 
 degree of differentiation. Taking first the vegetative 
 portion, we have in the thallus a structure that is 
 typically shown in lichens and other plants belonging 
 to the thallophytes. More strictly speaking the Mar- 
 chantia stem is only thalloid, for there are the rudi- 
 ments of leaves on its underside, while a true thallus 
 has no leaves. The prostrate position of the stem has 
 necessitated the specialization of the upper surface for 
 the purposes of assimilation and respiration, and the 
 lower surface for the absorption of moisture and the 
 other nourishment which comes with it. 
 
 The chlorophyll bodies, like those of all higher plants, 
 
7 8 COMMON LI VER WOR T. 
 
 consist of rounded grains of protoplasm in which the 
 chlorophyll proper is contained, the protoplasmic body 
 being readily seen after the pigment has been extracted 
 by alcohol. Such grains are scattered throughout the 
 thallus, but are only effectively developed in special 
 cells, which arise from the floor of cavities formed by 
 depressions in the surface of the thallus, and which are 
 overarched by the epidermis at a very early stage of 
 growth. 9 Communication with the outside air is 
 secured by means of peculiar and highly developed 
 stomata. 10 They are wider in the middle than at the 
 upper and lower openings, each stoma forming a small 
 air-chamber. The border to the outer opening is sharp 
 edged and immobile, while the inner one is formed of 
 inflated cells which act as regulators to the passage of 
 air and moisture. Altogether a very perfect arrange- 
 ment is thus made for the aeration of the chlorophyll 
 tissue without undue loss of moisture. 
 
 The under surface of the stem is provided with copi- 
 ous hairs, those of the wingsdeveloped to give support, 11 
 toward which the internal thickenings and spiral con- 
 striction of the walls contribute, while those of the mid- 
 rib, larger, smooth-walled, and somewhat colored, serve 
 to fix the plant to the earth and to take up from it the 
 water and nutriment required, i. e. to perform the 
 office of roots. In a physiological point of view 
 
 9 Leitgeb,Die Athemoffnungen cler Marchantiaceen, in Sitzber. d. k. k. 
 Akad. in Wien, Ixxxi, 1880. This differs from the older view which 
 ascribed the openings to a separation of the epidermis from the under 
 lying tissues. Sachs, Text-book ist and 2nd Eng. eds. 
 
 10 Described and illustrated by Voigt, Beitrag zur vergleichenden 
 Anatomic der Marchantiaceen in Bot. Zeit., 1879, P- 7 2 9- 
 
 11 According to Strasburger, Das botanische Practicum, p. 314. 
 
MARCHANTIA POLYMORPHA. 79 
 
 the root-hairs are not merely rhizoids but real roots, 
 and such they have been called by Sachs recently, who 
 no longer holds to the morphological distinctions of 
 root, stem, leaf and hairs, but refers all vegetative 
 organs of higher plants to two categories, viz : the root 
 and the shoot 
 
 The scales are organs that we shall meet with in a 
 more developed form when we reach the ferns. They 
 differ from the leaves in size and position, but more 
 especially in having the cells empty and lifeless. 
 
 The internal structure of the stem is interesting on 
 account of the thickenings of the cell-walls for secur- 
 ing extra strength, and the absence of any differentia- 
 tion of the tissues along the midrib except the moder- 
 ate change in the shape of the cells. 
 
 The branching of the stem is a fine example of true 
 dichotomy where the growing point is symmetrically 
 halved, and each half gives rise to a branch. 18 In this 
 case one branch develops faster than the other, and 
 the appearance is soon the same as if it had arisen as a 
 lateral branch (see fig. 2). The tissues of the wings 
 reach their growth more rapidly than those of the 
 midrib, and so the growing end is constantly indented. 
 
 The leaves have little of the appearance we associate 
 with the term, as commonly used. They are, indeed, 
 very depauperate leaves, and serve simply as organs 
 of strength, through the power of the protoplasmic 
 contents of the cells to maintain turgidity. 
 
 The asexual propagation in Marchantia is of two 
 
 "Vorlesungen uber Pflanzenphysiclogie, p. 5. 
 'Sachs, Text-book, 2nd Eng. ed., pp. 177, 181. 
 
8o COMMON LI VER IVOR T. 
 
 kinds. One is a very common method, by which the 
 stems die off at the older end as fast as they grow at 
 the other. In this way the branches are eventually 
 separated from each other and become independent 
 plants. The other is a peculiar method by which cer- 
 tain hairs at the bottom of cupules grow into flat green 
 plates, the gemmae, which as they become mature are 
 pushed out of the cupules by the aid of the secretion 
 from the glandular hairs. 14 The gemmae have their 
 direction of growth changed at a very early stage by 
 the formation of a right and left growing point, so that 
 the young plantlet is bifurcated at its outset. - When 
 a gemma has fallen upon the ground, the side which 
 happens to be uppermost is developed as the upper 
 surface of the thallus, and the other becomes the lower 
 surface. 15 The root-hairs grow from the cells devoid 
 of chlorophyll. 
 
 The sexual reproduction is among the most highly 
 developed of that shown by the liverworts. The organs 
 are upon branches whose modification is so interesting 
 that it will be necessary to examine it somewhat care- 
 fully. The plants are dioecious, bearing the reproductive 
 organs on separate individuals. In each case the repro- 
 ductive branch consists essentially of an attenuated por- 
 tion, the pedicel, terminated by an expanded portion, the 
 head, on which last the sexual organs are borne. The 
 pedicel is not a single branch, but two which are the 
 result of dichotomy at the point where it leaves the 
 
 14 Fide Strasburger, Das botanische Practicum, p. 436. 
 
 15 Engelmann, Ueber die Einwirkung des Lichtes auf den March- 
 antienthallus in Arb. d. bot. Inst. in Wurzburg, Bd< ii, p. 665 ; Mirbel, 
 Mem. Acad. Sci.de Fr., xiii (1835), p. 355. 
 
MARCH AX TI A POLYMORPHA. 8 1 
 
 thallus. These two do not separate, and, indeed, were it 
 not for the two double rows of leaves along the anterior 
 (under) surface, which give rise to the two grooves with 
 their strengthening hairs, it would be difficult to show 
 that any branching had occurred. 
 
 The pedicel of the female head is made up of exten- 
 sions of the tissues of the thallus, but without the 
 development of the wings. The head is formed by 
 sudden branching, and as dichotomous branching must 
 always be in pairs, it results in an even number of 
 branches which are spread out like a very widely open 
 fan. But counting the rays of the head always gives 
 an odd number, which is explained by the fact that the 
 growing point is not at the tip of the rays but at the 
 sinus between them, while the rays are formed, as in 
 the thallus, by the extension of tissue on either side 
 the growing point. Thus each ray, with the exception 
 of the ones nearest the cleft of the head, stands between 
 two growing points, while those next the cleft have a 
 growing point only on one side of them. The hairs of 
 the rays correspond with the hairs of the wings, and 
 extend into the grooves of the pedicel. 
 
 If now we turn to the male branch, we shall 
 find the pedicel only differs from that of the female in 
 possessing no chlorophyll tissue on its posterior (upper) 
 surface. The tissues of the upper surface of the head 
 were at an early period of growth continuous with those 
 of the thallus, but, owing to some unknown cause, they 
 have not continued to expand along with those of the 
 ventral side in forming the pedicel. The head is made 
 up of branches, as in the female head, and like that is 
 not a radial structure, but zygomorphic. The cleft is 
 
8 2 COMMON LI VER WOR T. 
 
 not so evident as in the other case, and the number of 
 rays is even and not odd, the latter being the result of 
 the growing point being at the ends of the rays, instead 
 of at the sinuses. The various correlated changes can 
 readily be worked out by the student. 
 
 It now remains to account for the position of the 
 two kinds of organs, one being on the upper surface 
 and the other on the lower. We must know in the 
 first place that the antheridia are modified hairs, which 
 originally started on the surface, but became inclosed 
 in cavities by the surrounding tissues growing up about 
 them. They evidently belong to the upper surface 
 from their position, and the fact that those nearest the 
 growing edge are the youngest. In the female inflor- 
 escence we find that the organs nearest the edge are 
 not the youngest, but the oldest. We can only explain 
 this by supposing that they belong to the upper sur- 
 face, but are brought below by the turning under of 
 the growing point. 16 The perichaetium is the thin ex- 
 panded edge of the thallus. 
 
 The antheridia and archegonia originate, as in the 
 case of the gemmae, from papilliform hairs, which divide 
 into two cells by a transverse wall, the lower cell becom- 
 ing the pedicel, and the upper the body of the organ. 17 
 Paraphyses, which are always sterile bodies, are very 
 common among the cryptogams; their significance is 
 not understood. 
 
 The antherozoids may be taken as the type of the 
 motile male element in fertilization. They are formed 
 
 16 Strasburger, Das botanische Practicum, p. 439; Leitgeb, Unter- 
 suchungen liber die Lebermoose, vi, 1881. 
 
 17 Sachs, Text-book, 2nd Eng. ed., p. 348. 
 
MARCHANTIA POL YMOKPHA. 83 
 
 of free protoplasm, having no cellulose covering. The 
 hyaline vesicle which is sometimes seen attached to 
 them arises from the internal part of the protoplasm 
 of the cell, the outer portion of which produces the 
 cilia, and the nucleus at the center of the cell the body 
 of the antherozoid. 18 
 
 The archegonia separate a mass of protoplasm in 
 their interior, the oosphere, which is essentially a naked 
 cell. After fertilization it divides in a perfectly regular 
 manner to form the sporogonium. The fertilization is 
 prepared for by the conversion of the axial row of cells 
 of the neck into mucilage, the swelling of which forces 
 the stigmatic cells apart, and a passage-way is formed 
 to the naked oosphere. The antherozoids pass through 
 this channel, become buried in the oosphere, and the 
 fertilization is complete. 
 
 The elaters by their strongly hygroscopic character 
 assist materially in forcing out and distributing the 
 spores." 
 
 18 Strasburger, Das botanische Practicum, p. 455. 
 
 19 The student should consult Ilofmeister's Higher Cryptogamia, which 
 contains a very full statement of the development of Marchantia, with 
 historical references up to 1862. 
 
MOSS. 
 Atrichum undulatum Beauv. 
 
 PRELIMINARY. 
 
 MOSSES appear so much alike to those who have not 
 given special attention to them, that it is more difficult 
 to definitely point out a particular species than in the 
 other plants of the book. The one selected for study 
 is widely distributed, and very common, forming carpet- 
 like patches in woods, and on shady banks. The single 
 plants stand from two and a half to four centimeters 
 (one to one and a half inches) high. The leaves, which 
 are abundant, are five millimeters (quarter of an inch) 
 or more long, narrow, with wavy sides ; the undu- 
 lations appear, when the leaf is held to the light, as lines 
 passing obliquely from the middle to the margin. 
 
 The male and female plants are usually found in sep- 
 arate patches, as in Marchantia. The male flowers (see 
 fig. 5) are easily recognized by being cup shape, and are 
 distinguished from the rosette of leaves terminating a 
 rapidly growing stem by having a distinct, rather flat 
 bottom to the cup. They are readily found at almost 
 any time during the year, and are especially abundant 
 in early summer. 
 
 The female flowers, which are less common than the 
 male, differ so little in external appearance from the 
 ordinary vegetative condition, that it often requires a 
 
A TR 'J 'CHUM UNDULATUM. 85 
 
 protracted search to find them. A patch of female 
 plants may usually be detected by the presence of the 
 fruit in some condition of growth or decay ; if, on cut- 
 ting vertically through astern taken from such a group 
 of plants, the terminal leaves of which are well folded 
 over the end, making a loose bud, the stem appears to 
 terminate abruptly within the bud, it may be inferred 
 that the female flowers are found. It is, however, 
 necessary to use the microscope to render it sure. 
 They are to be sought for especially in May. If the fe- 
 male flowers can not be found, those of other mosses will 
 answer the purpose. Polytrichum is one of the largest 
 of our mosses, and has female flowers much like Atri- 
 chum, while Mnijun, Funaria, and others have them 
 somewhat larger, more conspicuous, and nearly as com- 
 mon as the male. 
 
 The fruit is a nearly straight cylindrical pod with a 
 conspicuous pointed beak, borne erect on a stalk about 
 two or three centimeters (an inch) long (see fig. 4). Col- 
 lect both green fruit from which the hood (calyptra) has 
 not fallen, and that which is thoroughly ripe with the 
 hood and lid both gone, exposing the teeth. 
 
 The protonema is not so abundantly produced as in 
 many mosses. Keeping vigorous growing plants in an 
 inverted position in a moist atmosphere for some time 
 by turning a bell-glass over them, will sometimes be 
 sufficient to develop it. The protonema from other 
 mosses {Mnium^ Barbula, etc.) is, however, usually 
 found with ease, or may be produced as above, and will 
 serve for the study. 
 
 The materials required for the present study are 
 
86 MOSS. 
 
 alcoholic specimens showing male and female flowers, 
 and fruit ; fresh specimens showing protonema and male 
 flowers ; potassic hydrate ; and iodine. 
 
 LABORATORY WORK. 
 GROSS ANATOMY. 
 
 A. GENERAL CHARACTERS. Note 
 
 1. The vertical stem ; unbranched, or branching only from 
 the base. 
 
 2. The leaves clothing the stem. 
 
 3. The root-hairs, rhizoids ; often forming a close felt at 
 the base of the stem. 
 
 4. At the summit of some of the stems, Deflowering heads 
 of two sorts : 
 
 a. The male heads forming a terminal rosette of green 
 leaves. 
 
 b. The female heads with the terminal leaves folded 
 over each other forming a small bud. 
 
 5. At the summit of other stems the fruit or sporogoniuni, 
 consisting of 
 
 a. The slender stalk or seta. 
 
 b. The cylindrical pod or capsule. 
 
 c. The hood which fits closely over the end of the 
 pod, and may be easily pulled off, or has dropped 
 off of itself, the calyptra. 
 
 6. Among thrifty plants that have been kept under a 
 moist bell jar for several days, notice the green threads 
 growing out over the soil, the protonema. 
 
 B. THE RHIZOIDS. Remove some from the stem, 
 mount, and notice the small tangled hairs forming the mass. 
 
ATRICHUM UNDULATUM. 87 
 
 C. THE STEM. Notice * 
 
 1. The size and shape. 
 
 Remove the leaves near the base, mount a transverse sec- 
 tion, and notice 
 
 2. The outline of the section. 
 
 3. The three tissue regions ; the peripheral brown tissue, 
 the axial tissue forming a light spot in the center, and 
 the intermediate colorless tissue. 
 
 1). THE LEAVES. Notice 
 
 1. The manner of arrangement on the stem. 
 
 2. The difference in size on different parts of the stem. 
 
 3. The shape of 
 
 a. The lowest, scale leaves. 
 
 b. The middle, foliage leaves. 
 
 c. The uppermost on flowering stems, forming the 
 outer portion of the head, perichsBtial leaves. 
 
 4. The structure ; a thin lamina, with a thicker median 
 line, the midrib. 
 
 5. The character of the margin, especially toward the 
 apex. 
 
 6. In the foliage leaves, the undulations passing obliquely 
 outward from the midrib to the margin ; their absence 
 in the other sorts. 
 
 7. Draw a leaf of each sort scale, foliage and perichaetial. 
 E. THE FLOWERING HEAD. 1 
 
 i. The male heads. Notice 
 
 i Called the" receptacle" by Sachs (Text-book, 2nd Eng. ed., p. 370), 
 but this term has long been in use for the end of the stem on which the 
 parts of a flower are seated. The analogy of the several parts of the 
 moss " flower" to those of the head of a composite (e. g. sunflower) has 
 determined the use of corresponding terms. 
 
88 MOSS. 
 
 a. The shape. 
 
 b. The central disk. 
 
 c. The leafy continuation of the stem arising from the 
 center of some of the heads. 
 
 Cut a head in two vertically, and note 
 
 d. The enlarged end of the stem, receptacle, on which 
 the disk is seated. 
 
 e. Draw the half head, looking at the cut surface. 
 Remove the disk with the point of a scalpel, separate the 
 
 parts on a slide, mount, and notice 
 
 /. The broad chaff, resembling the scale leaves ; the 
 shape, especially the narrowed base. Draw. 
 
 g. Numerous narrow bodies of nearly the same 
 length as the chaff, antheridia, the male reproduc- 
 tive bodies. 
 
 h. Slender filaments of same length as the anther- 
 id ia, paraphyses. 
 2. The female heads. Make a vertical cut exactly 
 
 through the center, and notice 
 
 a. The absence of any thickening of the stem to 
 form an enlarged receptacle. 
 
 b. The absence of a disk. 
 
 Remove the central portion, separate well on a slide, 
 mount, and notice 
 
 c. The numerous filaments, the paraphyses. 
 
 d. A few bodies, not exceeding a half dozen, 3 about 
 as large as the antheridia, but swollen somewhat 
 near the base with the upper portion slender, the 
 archegonia, the female reproductive bodies. 
 
 F. THE FRUIT. Notice 
 
 8 The fewness of the archegonia, and the difficulty of securing them 
 at just the right stage of growth, often makes an extended search neces- 
 sary in order to demonstrate them. 
 
ATRICHUM UNDULATUM. 89 
 
 1. The stalk or seta. 
 
 a. The length. 
 
 b. Character of the surface. 
 
 c. The slightly expanded end from which the cap- 
 
 sule arises, apophysis. 
 
 Take a specimen that has been boiled a minute or two in 
 potassic hydrate, and pull the seta from the leafy portion, 
 taking care that it does not break off, but comes away 
 smooth, and notice 
 
 d. The pointed base. 
 
 2. The pod carried by the seta, the capsule, with its calyp- 
 tra ; notice 
 
 a. The manner in which the calyptra fits upon the 
 apex of the capsule. 
 
 b. Shape of the calyptra. 
 
 c. Pull away a calyptra and note its texture, and the 
 roughness of its apex. Draw. 
 
 d. The shape of the capsule, and nature of the sur- 
 face. 
 
 e. The hemispherical apex bearing a long beak, 
 together forming a removable lid, the operculum. 
 
 /. The obliquity and slightly eccentric position of the 
 
 beak. 
 
 . Draw a capsule. 
 //. Pull off the operculum from a mature fruit, and 
 
 notice the /-/;;/ of the capsule on which the edge 
 
 of it rested. 
 
 /. Rising from the rim, a large number of deli- 
 cate, incurved teeth, together forming the peri- 
 
 stome. 
 / Count the teeth ; the number will be some multiple 
 
 of four. 
 /-. The delicate epiphragm stretched between the 
 
 apices of the teeth ; to be better displayed shortly. 
 
go MOSS. 
 
 I. Draw the upper part of the capsule showing the 
 
 teeth and epiphragm. 
 
 Divide the capsule longitudinally, and notice 
 m. The axial column running through the center, the 
 
 columella, the expanded apex giving rise to the 
 
 epiphragm. 
 n. The cavity between the columella and wall of the 
 
 capsule, either empty or filled with a powder, the 
 
 spores. 
 o. Make a diagram of the section. 
 
 MINUTE ANATOMY. 
 
 A. THE RHIZOIDS. Under high power, notice 
 
 1. The straightness, uniformity of diameter, and mode 
 of branching. 
 
 2. The character of the lateral walls, and the position and 
 direction of the cross-partitions, if any. 
 
 3. Draw. 
 
 4. Notice the manner in which some of the rhizoids are 
 coiled around each other, forming ropes. 
 
 B. THE PROTONEMA. Notice 
 
 1. The arrangement of the cells. 
 
 2. The thinness of the walls, and position of the cross- 
 
 partitions. 
 
 3. The contents. 
 
 4. Draw. 
 
 C. THE STEM. In a transverse section taken from the 
 lower scaly part of the stem, notice 
 
 i. The three regions. 
 
 a. The peripheral, with the cell walls reddened. 
 
A TRICHUM UND ULA TUM. 9 l 
 
 b. The axial, with the cell walls colorless. 
 
 c. The intermediate, with cell walls yellowish. 
 
 2. '\\it peripheral tissue. Note 
 
 a. The outer layer, epidermis, occasionally bearing 
 
 root-hairs. 
 l>. The similar underlying cells, merging into 
 
 3. The intermediate region. Note 
 
 a. The larger cells with the walls becoming thinner 
 
 toward the center of the stem. 
 
 b. One or more leaf traces, composed of 
 
 i. A crescent shaped layer of small round cells 
 with very thick walls, the dorsal cells. 
 
 ii. Lying in the crescent, about two rows of 
 larger cells with rather thin walls, the conduct- 
 ing cells, inclosing 
 
 iii. Two or three small cells, appearing much 
 like intercellular spaces, the central cells. 
 
 iv. Still further toward the center of the stem, a 
 few scattered cells similar to the dorsal, the 
 basal cells. 
 
 c. Note that the leaf traces nearest the center of the 
 stem are the simplest. Sometimes one may be found 
 at the very center of the stem. 
 
 4. Draw one of the largest leaf traces with some of the 
 surrounding tissue including the adjacent epidermis. 
 
 5. Theaxia/ region. Note 
 
 a. The more or less strongly thickened walls of the 
 cells. 
 
 b. The small groups of cells with the intervening walls 
 very thin and membranous. 
 
 c. Draw a portion of the axial region. 
 
 6. In a longitudinal section of the stem, identify as many 
 of the different sorts of cells as possible, noticing 
 
02 MOSS. 
 
 a. The shape of the cells. Draw. 
 
 b. The direction taken by the leaf traces. 
 
 Remove the scales from a stem, cut a slice from the 
 surface, and notice 
 
 7. The shape of the epidermal cells. Draw. 
 
 D. THE LEAF. Make a transverse section just below the 
 middle of one of the largest foliage leaves, and notice 
 
 1. The larger central portion, the midrib. 
 
 2. The plate of cells, usually a single row, extending right 
 and left from the midrib, the lamina. 
 
 3. The midrib. Note. 
 
 a. The epidermis : a single layer of cells on the con- 
 vex (under) side ; a layer on the flat (upper) side, 
 each cell of which gives rise to a vertical plate, 
 two to four or more cells in height. If from a 
 fresh specimen, note the contents of the cells. 
 
 b. The leaf bundle; compare the several parts, the 
 dorsal, basal, central and conducting cells, with the 
 corresponding parts of the leaf trace which enters 
 the stem, already examined. 
 
 c. Occasionally a few cells between the dorsal and 
 basal cells and the adjacent epidermis, resembling 
 the latter. 
 
 d. Draw the midrib. 
 
 4. The lamina. Note 
 
 a. The shape and contents of the cells. 
 
 b. The smaller grouped cells at the margin of the 
 lamina. 
 
 c. Draw. 
 
 Mount a foliage leaf entire with the upper side upper- 
 most, and beside it another with the lower side, uppermost ; 
 using low power, notice 
 
 9 
 
A TRICH UM UND ULA TUM. 93 
 
 d. The cells of the main part of the lamina with their 
 contents. 
 
 e. The marginal cells, produced into 
 
 /. The sharp forward-pointing teeth, which are often 
 in pairs : observe the distribution of the teeth 
 along the margin, also similar teeth on the under 
 side of the leaf along the summits of the undula- 
 tions and on a part of the midrib. 
 
 g. The surface of the midrib : observe the shape of 
 the cells on the under side ; the rows of chlorophyll 
 tissue on the upper side, which begin near the base 
 of the leaf and extend nearly to the apex, seen as 
 plates in the transverse section. 
 Under high power, notice 
 
 //. The elongated marginal cells, and the shorter cells 
 forming the teeth. 
 
 /. Draw a portion from near the middle of the leaf, 
 showing teeth, marginal cells and some adjacent 
 laminal cells. 
 
 E. THE FLOWERING HEAD. Remove the disk from 
 a male head, and mount, well separated ; notice 
 
 1. Numerous hairs, \hzparaphyses. 
 
 a. The walls, cross partitions, and contents. 
 
 b. Draw. 
 
 2. The antheridium. 
 
 a. The shape. 
 
 b. The elongated cells of the body. 
 
 c. The short cells of the pedicel. 
 
 d. The large apical cell, in antheridia which have not 
 yet burst. 
 
 e. Draw. 
 
 3. The antherozoids. If from a fresh specimen, notice 
 
94 MOSS. 
 
 a. The movement. Apply iodine, and watch them as 
 they gradually come under its influence. 
 
 b. The form ; a slender body, with a pair of cilia at 
 the anterior end. 
 
 c. The colorless vesicle sometimes to be seen attached 
 to the posterior part. 
 
 d. Draw. 
 
 Crush an immature antheridium by pressing on the cover- 
 glass, and as the contents escape, notice 
 
 e. The antherozoids coiled within the mother-cell. 
 
 If alcoholic specimens are used, the antherozoids may be 
 seen within the mother-cell, but the parts can not be made 
 out. 
 
 Tear apart a female head, mount, and notice 
 
 4. The paraphyses j shape and structure. 
 
 5. The archegonia. 
 
 a. The enlarged ventral portion. 
 
 b. The long neck. 
 
 c. The short thick pedicel. 
 
 d. Focus upon the surface, and draw some cells of 
 each portion. 
 
 Treat with potassic hydrate to render the archegonia 
 more transparent, focus so as to give an optical section, and 
 notice 
 
 e. The two rows of cells forming the neck, the ter- 
 minal cells of which are 
 
 f. The stigmatic cells. 
 
 g. The canal along the axis of the neck. 
 
 h. The two or more rows of cells surrounding the 
 
 ventral portion. 
 i. The small mass of protoplasm lying deep in the 
 
 center of the ventral portion, the oosphere (if not 
 
 yet fertilized). 
 
ATRICHUM UNDULATi'M. 95 
 
 J. Draw. 
 F. THE FRUIT. 
 
 1. The seta. In a transverse section near the base, 
 
 notice 
 a. The outer portion of thick walled, deeply colored 
 
 tissue, passing abruptly into 
 /'. Loose, thin walled, colorless tissue. Within these 
 
 and almost completely separated from them 
 
 c. A core composed of the following tissues : 
 
 i. An outer row of large, round, thin walled cells, 
 ii. Adjoining this a layer of smaller angular cells 
 
 with walls somewhat thickened, and 
 iii. In the center, a few small cells with thin 
 
 colorless walls. 
 
 d. Draw a sector of the section. 
 
 e. Notice the shape of the epidermal cells in a sur- 
 face slice. Draw. 
 
 /. Examine several longitudinal sections, and deter- 
 mine as many of the tissues as possible. Draw. 
 
 2. The capsule. Make a transverse section through the 
 middle of an immature capsule. Under low power, 
 notice 
 
 a. Two parts, separated by a cavity : 
 
 i. The outer, the wall of the capsule. 
 ii. The inner, the axial cylinder. 
 iii. Uniting these, if not torn away in making 
 the section, delicate radial filaments. 
 
 b. The parts of the axial cylinder. 
 
 i. The narrow outer part, the wall of the spore 
 
 case. 
 
 ii. The large central part, the columella. 
 iii. A dark line separating the two, the mother- 
 cells containing the young spores. 
 
96 MOSS. 
 
 c. Make a diagram of the section. 
 Under high power, examine in succession 
 
 d. Each of the tissues enumerated. 
 
 e. Draw a sector of the section. 
 
 Make a transverse section of a mature capsule, notice 
 /. The thick walled, deep colored and strongly cuti- 
 
 cularized epidermis. 
 g. The colored cells of the spore sac. 
 Make a longitudinal section of a nearly mature capsule 
 (after removing the calyptra), and with low power, notice 
 at the base of the capsule 
 
 h. A mass of large thin walled cells forming the 
 
 apophysis. 
 
 i. Above the apophysis several layers of smaller, 
 more regular cells, from which arise the various 
 parts of the axial cylinder. 
 j. At the upper end of the capsule, notice 
 
 i. The large central mass of wide thin walled 
 cells, resting upon the axial cylinder and 
 inclosed by the operculum. . 
 
 ii. The line of separation between this and the 
 roof of the operculum, showing, more or less 
 clearly, the delicate membrane which is ex- 
 posed by the detachment of the operculum, 
 the epiphragm. 
 iii. The small deeply colored cells of the rim of 
 
 the capsule. 
 
 iv. The curved lines extending from the rim 
 to the edge of the epiphragm, the structure 
 usually not well shown, the teeth of the peri- 
 stome. 
 
 v. The tissue of the operculum on the sides 
 where "it shuts over the teeth, of the roof 
 adjoining the epiphragm, and of the beak. 
 
A TRICHUM UND ULA TUM. 97 
 
 /-. Illustrate the arrangement of the tissues as seen 
 
 in longitudinal section by a diagram. 
 Take a nearly mature capsule, remove the thinnest pos- 
 sible slice from the side of the operculum with the razor 
 inclined toward the beak ; the next slice will include a por- 
 tion of the peristome, in which notice 
 
 /. The rows of cells from which the teeth are 
 formed, and their manner of thickening. Draw. 
 Make several transverse sections through the rim and 
 operculum, and study 
 
 m. The formation of the teeth from groups of cells. 
 Take a mature capsule, mount a number of entire teeth, 
 and notice 
 
 //. The shape and structure of the teeth. Draw. 
 o. Flatten out a calyptra, and observe the cellular 
 structure, especially at the apex. Draw some 
 of the cells. 
 
 3. The mature spores ; note under high power 
 a. The shape. 
 A The wall and contents. 
 
 ANNOTATIONS. 
 
 The step from Marchantia to Atrichum is not so 
 great as that which intervenes between the several 
 preceding examples, and yet the advancement is well 
 marked and especially significant. With the upright 
 growth of Atrichum is correlated the disposition of the 
 leaves and root-hairs. The leaves being green, relieves 
 the stem of its assimilative duties, and in consequence 
 the smaller size and greater firmness better meet the 
 requirements. The root-hairs simulate true roots even 
 
98 MOSS. 
 
 more closely than those of Marchantia. A curious 
 habit of the root-hairs of this and the allied genera is 
 the manner in which they coil about each other, form- 
 ing branching ropes, and adding to their effectiveness 
 as hold-fasts. 
 
 The stem of Atrichum shows considerable diversity 
 of tissues. The axial groups of cells with thin inter- 
 mediate walls are peculiar to a few of the higher 
 mosses. A noticeable feature is the absence of a well 
 marked epidermis, which is doubtless to be associated 
 with the fact that the cells beneath have thick walls, that 
 there are no chlorophyll tissues to be aerated, and that 
 the numerous leaves assist materially in giving protec- 
 tion. The absence of stomata is also to be accounted 
 for by the absence of chlorophyll tissues. 
 
 The leaves show a distinct midrib and blade, and 
 possess all the essential features of true foliage leaves. 
 The blade being only one cell thick is apparently the 
 same on both sides, and possesses chlorophyll bodies 
 which are typical for all higher plants. A selvage of 
 strong cells runs around the edge of the lamina to 
 guard against tearing, while numerous teeth act, to 
 some extent, as a protection. To give additional aerat- 
 ing surface, there are a number of plates, like narrow 
 auxiliary blades, placed along the upper surface of the 
 midrib. They are still better developed in Polytri- 
 chnm y but are entirely wanting in most mosses. As 
 there is no epidermis or other protective structure to 
 guard against excessive evaporation, an ingenious sub- 
 stitute is afforded by the inrolling of the sides of the 
 leaf whenever the turgidity of the cells is disturbed. 
 
 But no feature in the histology of mosses is more 
 
A TRICHUM UXDULA TL MA 99 
 
 significant and interesting than the leaf bundle of the 
 midrib. It is the simplest form of a structure that 
 plays a most important part in higher plants the 
 framework of wood and bark which enables them to rise 
 above the surface of the earth and display their tissues 
 to the wind and sun under conditions most favor- 
 able for growth. The bundles of Atrichum which are 
 as highly developed as in any of the mosses, resemble 
 those of higher plants more in their position and 
 function than in structure. 8 Their place in the leaf 
 and their manner of forming leaf-traces in the stem are 
 like those of higher plants. The cells for strength are 
 the dorsal and ventral, being the same except in posi- 
 tion, and the cells inclosed by these transport the sap. 
 
 Passing to the sexual reproduction, we notice that 
 the organs concerned are much like those of Marchantia. 
 The differences requiring consideration lie in the modes 
 of displaying and protecting the organs. Instead of 
 sinking the male organs in a flattened receptacle, they 
 are placed in the axils of protecting leaves diverted to 
 that use, and instead of bringing the female organs 
 under the protecting roof of the receptacle they are 
 sheltered from rain and other excessive moisture by 
 the overlapping of the perichaetial leaves. 
 
 An item of historical interest in this connection is 
 that it was in the mosses that the sexual organs of 
 cryptogams were first demonstrated by Hedwig 4 in 
 1783, but it was not till the publication of Suminski's 
 researches on the ferns, 5 as late as 1848, that their 
 
 3 A very full illustrated account of the histology of the stem and leaves 
 of mosses is given in Pringsheim's Jahrb. f. wis. Bot., vi. 
 
 4 Theoria Generationis, p. 138. 
 
 5 Zur Entw. der Farrnkrauter. 
 
100 MOSS. 
 
 sexual character was fully established. It was also in 
 mosses and liverworts that the antherozoids were first 
 detected, being seen by SchmideP in 1762, but without 
 detecting their cilia, which were discovered by Unger 7 
 in 1837. 
 
 After fertilization has occurred the oosphere clothes 
 itself with a cell wall, and grows at once into a fruit, as 
 in Marchantia. This fruit is in many ways remarkable, 
 as will be more apparent in some respects after study- 
 ing the ferns and club-mosses. It will be remembered 
 that in the plants already studied, with the exception 
 of Marchantia, the sexually formed spore produced a 
 plant like the parent, after a longer or shorter period of 
 rest. In Atrichum, however, it grows, not into a plant 
 like the parent, but into a highly complicated structure, 
 the fruit or sporogonium, which in its turn forms 
 asexual spores that produce plants like the original. 
 This process, known as an alternation of generations, 8 
 is less strongly marked in liverworts, and reaches 
 its height in ferns. 
 
 The base of the seta which is thrust into the apex of 
 the leafy plant, has no organic connection with it, and 
 while in Atrichum it pulls out with some difficulty, in 
 many mosses it comes away easily without preparatory 
 treatment. This feature further emphasizes the dis- 
 tinctness of the so-called fruit and the parent plant, 
 from which in quite a parasitic fashion it derives its 
 nourishment. 
 
 6 Icones plantaram, p. 85. 
 
 7 Nova Acta A. C. L.-C. Nat. Cur., xviii, p. 791. 
 
 8 Sachs, Text-book, 2nd Eng. ed. , pp. 226,954; Vines, Journal of 
 Botany, 1879 ; Underwood, Our native ferns and their allies, p. 35. 
 
ATRICHUM UNDULATUM. lot 
 
 The tissues of the seta attain rather higher devel- 
 opment than those of the stem. The cortical part is 
 provided with a well formed epidermis, while the axial 
 part is composed of several tissues, the two portions 
 being separated by thin-walled parenchyma. At the 
 apophysis, where the seta expands at its upper end, 
 many mosses produce stomata quite like those of 
 higher plants. In rarer instances they occur on the 
 capsule or seta. Their presence or absence seems to 
 signify nothing as to relationship, as there is no more 
 constancy in their occurrence among the highest than 
 among the lowest forms." 
 
 The capsule of Atrichum does not differ widely from 
 that of other mosses, except in the teeth and epi- 
 phragm, and otherwise requires no particular explana- 
 tion. The teeth are composed of groups of cells 
 arranged as a series of U's placed side by side. In all 
 other mosses except the immediate allies, where teeth 
 are present at all, they are formed of the thickened 
 sides of the cells, and not of whole cells. 10 The epi- 
 phragm, which joins the apices of the teeth like a thirf 
 membrane, is formed without thickening or special 
 preparation of the walls. The spores escape by being 
 shaken from the capsule through the openings between 
 the teeth, as from a pepper box. 
 
 The calyptra, which is the result of the aftergrowth 
 of the archegonium, was early torn away from its 
 attachment at the base of the fruit and carried up by 
 the elongating seta as a hood for the capsule. 
 
 9 Valentine, Trans. Linn. Soc. , xviii, p. 239. 
 
 10 Sachs, Text-book, 2nd Eng ed., p. 383. 
 
102 MOSS. 
 
 The spores germinate by producing a protonema, 
 which may grow to considerable length, with numerous 
 branches, before a leafy stem is formed. The successive 
 inclinations of the transverse walls of the protonema 
 have been shown to follow the same laws as govern the 
 successive divisions of the apical cell to form the leafy 
 stems, so that we are to consider the protonema as an 
 excessively attenuated stem, from which the leafy stems 
 arise as lateral branches. 
 
THE MAIDEN-HAIR FERN. 
 
 A dia n t u ui pe da tuin L . 
 
 PRELIMINARY. 
 
 THE maiden-hair fern is abundant in dark rich woods 
 throughout the eastern part of the United States, and 
 occurs to a considerable extent west of the Rocky 
 Mountains. It may be recognized with certainty by the 
 forking of the polished purple leaf-stalk into two equal 
 recurved branches, which give rise to a number of 
 straight branches upon one side, bearing the oblong 
 leaflets. On the back of the leaflets, along their mar- 
 gins, are born the crescent-shaped fruit dots. 
 
 Underground stems and roots (together popularly 
 called roots), and leaves, including the leaf-stalks, should 
 be collected when the fruit dots assume a yellowish 
 brown hue, which is usually about the middle or latter 
 part of August. The roots should be taken up with 
 care and the dirt shaken from them gently to avoid 
 tearing off the root-hairs and root tips, and the clean- 
 ing completed with water. Part of the leaves and all 
 of the stems and roots should be preserved in alcohol, 
 the remainder of the leaves by drying between news- 
 papers or in a plant press. 
 
 The prothallia of Adiantum are less known popu- 
 larly. They are flat, roundish, green bodies, two 
 to five millimeters ( l / lt to l / B inch) in diameter, 
 
104 MAIDEN-HAIR FERN. 
 
 deeply notched on one edge, and held to the 
 ground by a cluster of root-hairs from the under 
 side. They may be found on the surface of 
 damp ground near patches of the fern, and may be 
 collected and preserved in alcohol. If a green-house 
 is accessible, prothallia may usually be obtained 
 fresh and in quantity from the surface of pots and 
 earth near which native or exotic species of Adiantum 
 are growing. If neither source yields suitable material, 
 the prothallia may be grown by sowing the spores of 
 Adiantum (to be obtained from the fruit dots on the 
 margins of the leaflets) on the surface of damp earth 
 packed smooth and kept at first under a bell-glass in a 
 good light. 1 Strasburger 3 recommends sowing the 
 spores on the surface of a piece of pressed peat (pre- 
 viously boiled in water to destroy other spores) which 
 is to be kept saturated with a nutritive solution pre- 
 pared according to the formula given on page 34. The 
 peat should be covered by a bell-glass and placed near 
 a north window. If prothallia of Adiantum can not be 
 obtained, the prothallia of almost any fern will show 
 the characteristic features of this stage. 
 
 It will be advisable before attempting to cut sections 
 of the rhizome to soak it for a few minutes in water in 
 order to soften the tissues somewhat, for when taken 
 from alcohol they are extremely hard. Care will have 
 to be exercised in cutting these sections not to nick the 
 edge of the razor ; it will need frequent sharpening. 
 Before cutting the sections, the end from which they 
 are to be cut should be smoothed with a knife. 
 
 1 Cf. Campbell, Bot. Gazette, x, p. 356. 
 
 2 Das botanische Practicum, p. 457. 
 
ADI A NTUM FED A TUM. 1 05 
 
 The requisites for the complete study of this plant 
 are dried and alcoholic specimens of leaves ; alcoholic 
 specimens of roots and stems ; fresh prothallia ; alco- 
 hol ; iodine ; potassic hydrate ; and solution of potassic 
 chlorate. 
 
 LABORATORY WORK. 
 GROSS ANATOMY. 
 
 A. GENERAL CHARACTERS. Taking a complete 
 plant, notice the four parts into which it may be readily 
 divided : 
 
 1. The horizontal, very dark brown, or almost black, un- 
 der-ground stem, the rhizome, from which are given off 
 
 2. A number of slender branching fibers, the roots. 
 
 3. The aerial portion, the leaf or frond, consisting of 
 slender polished stalks, and flat green expansions, the 
 
 blades. 
 
 4. The appendages to the surface, trichomes, in the form 
 of scales on the rhizome, hairs on the roots, and repro- 
 ductive bodies on the leaves. 
 
 B. THE STEM or RHIZOME. Notice 
 
 1. The size, shape and surface. 
 
 2. The occasional branching. 
 
 3. The nodes and internodes ; the nodes are indicated by 
 the growth of a leaf at each, alternately on the right 
 and left sides ; the intervals between the nodes are the 
 internodes. 
 
 4. The growing apex ; the dying base. 
 
 5. The buds near and at the apex. Strip off carefully 
 
io6 MAIDEN-HAIR FERN. 
 
 from several buds the numerous brown scales which 
 clothe them. Note the two kinds : 
 
 a. Buds showing a rudimentary leaf whose stalk is 
 coiled upon itself, thus : ^ 
 
 b. One or more buds whose central part is simply a 
 continuation of the stem. 
 
 6. Make an outline drawing of the rhizome, showing the 
 size, shape, mode of branching and arrangement of 
 leaves and buds. 
 
 7. The structure. Cut across the rhizome at right angles 
 to its length and examine the cut surface. Observe 
 
 a. The outer ring of brown tissue, the cortical layer. 
 
 b. The oval, circular, or C -shaped white mass, the 
 fibro-vascular bundle. Where a branch or leaf 
 arises two fibro-vascular bundles will be seen, thus : 
 C ^- Find a part of the rhizome showing such an 
 arrangement, and trace the course of the bundles 
 (by cutting a series of rather thick sections) through 
 at least two internodes, noting the modes in which 
 successive branches are given off from the bundle. 
 The smaller C -shaped portion passes into the 
 nearest leaf ; the other gradually enlarges, closes 
 into a circle, elongates into an oval, becomes egg- 
 shape, and finally opens to form two unequal C ' s 
 the smaller of which soon enters the second leaf on 
 the opposite side of the rhizome from the first. 
 
 c. Inclosed by the fibro-vascular bundle a darker 
 brown mass not differing otherwise from that sur- 
 rounding the bundle. 
 
 d. Make an enlarged drawing of the cut end of the 
 stem. 
 
 Cut a rhizome longitudinally through the center, and on 
 the cut surface make out 
 
ADIANTUM PEDA TUM. 1 o 7 
 
 e. The parts previously seen in the transverse sec- 
 tion. Draw. 
 
 /. The scales. Mount a few scales from the rhizome, 
 and note 
 
 i. Their shape and texture. 
 ii. Their structure j the shape and arrangement of 
 
 the cells, 
 iii. Draw a scale enlarged. 
 
 C. THE ROOTS. Notice 
 
 1 . The shape. 
 
 2. The mode of branching. 
 
 3. Their /#.//<?// on the rhizome. 
 
 4. The covering of tangled root-hairs with which some are 
 enveloped. 
 
 5. The absence of root-hairs near the w\i\\\s\\ growing end. 
 
 6. The brownish tip (sometimes torn off), the root-cap. 
 
 7. Examine a tranverse section of a root, and compare 
 with that of the stem. Note the position of the fibro- 
 vascular bundle. Draw the section. 
 
 D. THE LEAF. It may be easily distinguished into two 
 parts, the stalk, rhachis, with its branches, and the green 
 blades, pinnules. 
 
 i. The main rhachis and its branches. Note 
 
 a. The polished surface. 
 
 b. The shape ; a little flattened on the anterior sur- 
 face (i.e., the one corresponding to the upper sur- 
 face of the leaf). Dried or alcoholic specimens 
 are likely to have this surface flat or concave while 
 the posterior remains convex. Note the slight 
 
MAIDEN-HAIR FERN. 
 
 ridges between these two surfaces, more marked 
 in dried or alcoholic than in fresh specimens. 
 The color of the anterior and posterior surfaces. 
 The branching. At the top the rhachis divides 
 into two equal (or almost equal) divergent 
 branches. Each of these again divides into two, 
 one of which forms the rhachis of a pinna (to be 
 described shortly), while the other again forks. 
 Note the number of times such forking occurs and 
 the relative length of the secondary rhachises thus 
 formed. Make a diagram showing the above 
 points. 
 
 e. The structure. Cut transverse sections of the stalk 
 at various heights. Make out the same structure 
 as detailed for the rhizome. Notice 
 
 i. That the brown tissue of the stem is largely 
 
 replaced by a whitish one, parenchyma. 
 ii. The different shape of the sections of the 
 
 fibro-vascular bundle at various heights 
 
 along the stalk, 
 iii. Trace its course near the forking of the 
 
 stalk until it divides, one-half entering each 
 
 branch, 
 iv. Make diagrams showing these points. 
 
 f. Compare the scales on the base of the leaf-stalk 
 with those studied from the rhizome. 
 
 The pinna. Each pinna is composed of a slender pol- 
 ished rhachis bearing a number of leaflets, the pinnules. 
 Note the variation in the number of pinnules on a 
 rhachis and the general outline of a pinna. Make an 
 outline drawing of a pinna. 
 
 Theflinnutes. Selecting a pinnule near the middle of 
 the rhachis, observe 
 
PEDATUM. 109 
 
 a. The shape as to outline and margin. 
 
 b. Draw carefully an outline of the pinnule studied. 
 
 c. Compare the shape of the terminal pinnule with 
 those near the middle of the rhachis. Note that 
 it is like two of the latter joined by their bases. 
 Compare also the basal pinnules with the middle 
 ones. Draw an outline of the terminal and basal 
 pinnules. 
 
 d. The surface, texture, and color. 
 
 e. The structure. Notice 
 
 i. The slender stalk at the angle formed by 
 the lower and basal edges, attaching the pin- 
 nule to the rhachis. 
 
 ii. The slender branching threads, veins, ex- 
 tending from the apex of this stalk and 
 supporting 
 
 iii. The green substance of the pinnule, the mes- 
 ophyll, which fills all the space between the 
 veins. 
 /. The arrangement of the veins, venation. Notice 
 
 i. One vein a little stronger than the rest, par- 
 allel with and close to the lower edge. 
 The mode of branching. 
 That the veinlets are not connected into a 
 network. 
 
 iv. Compare with the venation of the basal and 
 terminal pinnules. 
 
 v. In the outline drawings of the terminal, basal 
 and middle pinnules already made draw the 
 veins. 
 
 4. The reproductive bodies. Observe 
 
 a. On the upper edges of the under side of the pin- 
 nules a large number of crescent shaped spots, 
 
1 1 o MAIDEN-HAIR FERN. 
 
 sori. Note the pinnules from which they are most 
 uniformly absent. 
 
 Soak a pinnule in water for a few minutes and with the 
 needles turn back 
 
 b. The flap which covers a sorus, the indusium. Notice 
 that it is a portion of the edge of the pinnule 
 reflexed and peculiarly modified. 
 
 c. On the under side of the indusium, a mass of yel- 
 lowish spheroidal bodies, the sporangia. 
 
 Scrape away most of the sporangia from the surface, and 
 notice 
 
 d. The relation of the points of attachment of the 
 sporangia to the veins. Cut off and draw an indu- 
 sium showing this. 
 
 5. The sporangia. Mount some of the separated sporan- 
 gia and examine by oblique light. Note 
 
 a. Their shape. 
 
 b. The short stalk by which they were attached. 
 
 c. The ridge, slightly darker than the rest, extending 
 part way round the sporangium, the annulus. 
 
 d. Burst a sporangium and note the contents, minute 
 powdery bodies, the spores. 
 
 c. Study the manner of bursting and scattering the 
 spores. Tear a bit of an indusium from a dried 
 specimen previously soaked in water, retaining 
 only a few sporangia ; place it on a slip of glass 
 and allow it to dry, while watching the sporangia 
 through a lens, illuminating them from above. A 
 crack appears on the side where the annulus is 
 absent, which gapes more and more as the annulus 
 straightens and becomes recurved. After bending 
 backward a certain distance, by a sudden jerk 
 whereby the spores are scattered, the annulus 
 
ADIANTUM FED A 7 I '.]/. 1 1 1 
 
 becomes straight again (or almost so), and very 
 gradually resumes the same position as before the 
 rupture of the sporangium. 
 
 E. THE PROTHALLIUM. Examine prothallia of 
 various ages. Notice 
 
 1. The shape and size. 
 
 2. The cellular structure, best seen in a mounted speci- 
 men. 
 
 3. The cluster of rhizoids on the under side. 
 
 4. That in a prothallium with a young fern plant attached 
 the plant arises from the under surface. 
 
 5. Draw. 
 MINUTE ANATOMY. 
 
 A. THE STEM. Cut a transverse section and examine 
 with a low power. Make out the following parts : 
 
 1. The single outer row of cells, the epidermis. 
 
 2. A considerable thickness of brown 1 thick-walled tissue, 
 the peripheral sclerenchyma. 
 
 3. A circular, oval or Q -shaped mass of whitish tissue, 
 most of which is \fatfibro-vascnlar bundle. 
 
 4. Surrounding this bundle, and marking its outline, a 
 chain-like row of minute oval cells, the bundle-sheath. 
 
 5. Entirely or partially surrounded by the fibro-vascular 
 bundle, a mass of axial sclerenchyma similar to the peri- 
 pheral. 
 
 Examine the section with a high power and study in 
 
 Yellowish in very thin sections. 
 
*l* MAIDEN-HAIR FERN. 
 
 detail each of the tissues and groups of tissues seen above, 
 in the following order : 
 
 6. The epidermis. Observe 
 
 a. That the outer wall is thicker than the lateral and 
 inner ones. In favorable sections a very thin 
 layer, the cuticle, may be seen covering the outer 
 wall. 
 
 b. That the epidermal cells contain numerous round- 
 ish or somewhat angular starch granules? Treat a 
 freshly-cut section with iodine, and notice the 
 color produced. 
 
 i. Study one of the starch grains. Notice the 
 central lighter spot, the nucleus. 6 
 
 c. Draw several epidermal cells. 
 
 7. The sclerenchyma, peripheral and axial. Note 
 
 a. How greatly the walls are thickened. 
 
 b. That adjoining walls consist of three or more dis- 
 tinct layers, the thin central one of which is the 
 middle lamella. 
 
 c. The perforations or pits, which extend through the 
 thickening layers to the middle lamella at right 
 angles to the surface of the wall. Observe that 
 the pits in contiguous cell walls correspond to 
 one another. 
 
 d. Examine the middle lamella at a point where three 
 or four cells meet. Note that it divides, inclosing 
 a triangular or quadrangular space which is filled 
 
 4 The occurrence of starch in epidermal cells is unusual. 
 
 6 The term as here used has an entirely different signification from 
 that which it has as applied to a cell. Here it denotes a central watery 
 spot, about which lie the layers of the starch grain, alternately more and 
 less watery. 
 
ADI A A r T UM PEDA TUM. 1 1 3 
 
 with a thickening deposit, similar to that of the 
 
 inner layers of the wall. 
 e. The abundance of starch in this tissue. 
 /. Draw several sclerenchyma cells showing these 
 
 points. 
 
 8. The cortical parenchyma^ lying just outside the bundle- 
 sheath in some places. Observe 
 
 a. That the walls are thin and colorless, with trian- 
 gular intercellular spaces ; contents of the cells, 
 granular protoplasm and starch. 
 
 b. Compare carefully the middle lamella of the 
 sclerenchyma with the walls of the parenchyma 
 where the two tissues merge. 
 
 c. Draw several parenchyma cells. 
 
 9. The bundle-sheath. Notice the emptiness 8 of the cells, 
 their shape, and the position of their longer axes. 
 
 10. The fibro-vascular bundle; easily distinguishable into 
 two regions : first, a central one, the xylem, char- 
 acterized by the numerous large openings of the 
 scalariibrm vessels, with small cells, the xylem paren- 
 chyma, packed between them ; secondly, a peripheral 
 one, the phloem, showing cells of much more uniform 
 diameter, and lying between the xylem and the bundle- 
 sheath. This region contains phloem parenchyma and 
 sieve cells, Study carefully each of the above 
 named tissues. Commencing at the bundle-sheath, 
 examine 
 
 a. The phloem parenchyma ; composed of two or three 
 (occasionally but one) irregular rows of small thin- 
 walled cells next the bundle-sheath and a few cells 
 
 6 Sometimes a few starch grains appear to lie in them ; they have been 
 pulled over by the razor in cutting. 
 
H4 MAWtf-HAlR FERN". 
 
 here and there between the sieve cells (to be 
 pointed out directly), all filled with granular pro- 
 toplasm and small starch grains. Compare with 
 cortical parenchyma. 
 
 b. The sieve cells ; lying between the main body of 
 phloem parenchyma and the scalariform vessels. 
 Note their angular shape, slightly thickened walls 
 and emptiness, except for a little granular material 
 clinging to the walls. 
 
 c. The scalariform vessels. Observe 
 
 i. That wherever two vessels are in contact their 
 contiguous walls are flattened, and the vessels 
 are therefore irregularly polygonal, having 
 two or three sides much longer than the 
 others. 
 
 ii. That they are thicker at the angles than on 
 the sides, and thus appear to be united only 
 at the angles. 
 
 iii. The narrow slit between the contiguous sides 
 of the vessels. 
 
 iv. The emptiness of the vessels. 
 
 d. The xylem parenchyma; small cells packed between 
 the scalariform vessels, and similar ones near their 
 periphery. Note their contents. 
 
 e. Notice the general arrangement of the tissues, 
 making it a concentric bundle. 
 
 /. Draw sufficient of the fibro-vascular bundle and 
 its sheath to show the different tissues and their 
 relations to one another. 
 
 Cut a longitudinal radial section of the stem in the plane 
 of the leaf stalks. Examine with a low power, and make 
 out 
 
 ii. The epidermis. 
 
ADIANTUM PEDA TUM. 1 1$ 
 
 12. The sclerenchyma, peripheral and axial. 
 
 13. The double band of whitish tissue, consisting of cortical 
 parenchyma, bundle-sheath and fibro-vascular bundle. 
 
 Examine the section with a high power, studying each 
 tissue seen in the transverse section. 
 
 14. The epidermis ; compare the length of its cells with 
 the same in transverse section. Draw a few cells. 
 
 15. The sclerenchyma ; cells elongated with tapering ends. 
 Note the pits and the middle lamella as in transverse 
 section. The mouths of the pits may be seen when a 
 wall extends across a cell. Draw. 
 
 1 6. The cortical parenchyma; as in transverse section 
 except that the cells are elongated. 
 
 17. The bundle-sheath ; the length and narrowness of the 
 cells. 
 
 18. The fibro-vascular bundle ; the two regions distin- 
 guished in transverse section, xylem and phloem. 
 Commencing at the bundle-sheath notice 
 
 a. The phloem parenchyma ; much as in the former 
 section. 
 
 b. The sieve cells ; their great elongation, tapering 
 ends overlapping succeeding ones, and slightly 
 thickened walls. Note the sieve plates on the 
 side walls, looking like irregular thin spots with 
 fine specks in them; or the sections of them on the 
 cut edges of the vessels, as depressions of the sur- 
 face of the wall, paired, one on each side when 
 two sieve vessels are contiguous. 7 
 
 c. The scalariform vessels. Observe 
 
 7 Under a or ^ objective the pores in the sieve plates may be bet- 
 ter seen. Consult Bessey, Botany, fig. 71, p. 81. 
 
1 16 MAIDEN-HAIR FERN. 
 
 i. That the walls of these vessels present many 
 narrow thin spaces, looking like slits placed 
 transversely. 
 
 ii. That these thin spaces do not extend entire- 
 ly across the face of a vessel. 
 
 iii. Find a place where the contiguous walls of 
 two vessels have been cut through by the 
 razor and observe the beaded appearance of 
 the walls. Each "bead " corresponds to the 
 thick part of the wall and the intervals to the 
 thin places. 
 
 Isolate some scalariform vessels by boiling a rather thick 
 longitudinal section for a few seconds in potassic chlorate 
 solution. Mount in water and examine with a high power 8 
 
 iv. The shape and markings. Draw. 
 d. Draw the fibro-vascular bundle with a portion of 
 the bundle-sheath. 
 
 19. The trichomes, in the form of scales. Mount scales of 
 various shapes under the same cover, and observe 
 
 a. The shapes and arrangement of the cells, espec- 
 ially at the apices of the scales. 
 
 b. Draw a scale. . . 
 
 B. THE ROOT. Cut a transverse section of one of the 
 larger roots, examine with a high power, and note 
 
 1. At the edge of the section (if perfect) the epidermis? of 
 irregular thick-walled cells, not differing much from 
 
 2. The underlying brown parenchyma, which gradually 
 merges into 
 
 8 If the vessels do not separate in mounting, press gently on the cover- 
 glass with a little sidewise push. 
 
 9 So called here because of its position ; not necessarily homologous 
 with the epidermis of the stem. 
 
ADI A N TUM FED A 7 Y J/. I I 7 
 
 3. Yellowish sclercncJiyma, similar to that of the rhizome. 
 Notice the starch, increasing in quantity toward the 
 center. 
 
 4. Draw a portion of the above tissues. 
 
 5. Note the abruptness with which the sclerenchyma joins 
 
 6. The fibro-vascular bundle. Notice the sheath which 
 encircles it. 10 
 
 a. Just within the bundle-sheath, a row of parenchy- 
 ma cells with granular contents (protoplasm) ei.cir- 
 cling the bundle, the pericambium. 
 
 b. The xylem region consisting of 
 
 i. Scalariform vessels ; four (sometimes three or 
 five) of which, occupying the center of the 
 bundle, are in pairs, one pair larger than the 
 other ; the remainder, much smaller, are in 
 t\vo clusters, one between the vessels of the 
 smaller pair and the pericambium on each 
 side. If the scalariform vessels are not easily 
 made out, a section may be treated with pot- 
 ash or stained with iodine. They then become 
 very plain. 
 
 ii. Xylem parenchyma; packed between and imme- 
 diately around the larger vessels. 
 
 c. The phloem region ; its two parts separated by 
 the xylem, lie outside of the vessels of the larger 
 pair and consist of parenchyma with granular con- 
 tents and empty sieve vessels. 
 
 7. Considering the whole bundle, notice that all the tis- 
 sues it contains are symmetrically disposed about a cen- 
 ter. It is therefore known as a radial bundle. 
 
 10 The bundle sheath frequently breaks in cutting. 
 
n8 MAIDEN-HAIR PERM. 
 
 8. Draw the bundle. 
 
 Take one of the largest roots whose root-cap is present 
 and cut a series of longitudinal sections, mount, treat with 
 potash, and selecting the section which passes through the 
 center of growth, note 
 
 9. The concentric layers of the root-cap, each thickest in 
 the middle, the outer sloughing off. 
 
 10. The tissues at the apex of the root. In the center, im- 
 mediately under the root-cap, a large triangular cell, 
 apex inward, the apical cell. Notice that the cells 
 adjacent to the inner faces of the apical cell have evi- 
 dently been derived from it by partitions parallel to its 
 faces. 
 
 11. Draw the tip of the root, including the root-cap. 
 
 12. The trichomes in the form of root-hairs. Slice off from 
 a root a thin piece carrying a number of hairs, and 
 note 
 
 a. Their attachment to epidermal cells. 
 
 b. The shape of a hair near the proximal and distal 
 ends. 
 
 c. The color of the wall and absence of septa. 
 
 d. The occasional spiral thickenings in the large hairs, 
 usually forming a loose spiral of three or four 
 turns only. 
 
 <?. The contents. 
 
 f. Draw a hair showing these points. 
 
 C. THE LEAVES. 
 
 i. The epidermis. Lift the epidermis of the lower surface 
 of a leaflet with the point of a needle, seize it with fine 
 forceps and strip off as much as possible, mount, 
 examine with high power, and notice 
 
ADIAXTUM PEDATUM. HQ 
 
 a. The very irregular shape of the cells and the way 
 in which they dovetail into each other. 
 
 b. Here and there narrow slit-like stomata, each 
 bounded by two crescentic cells, the guard cells. 
 
 c. Along certain lines (over the veins) the different 
 shape of the cells. 
 
 J. The chlorophyll bodies, especially in the guard cells ; 
 their granular nature. 
 
 e. Make a drawing showing these points. 
 
 /. Examine in the same way the epidermis of the 
 upper surface of a leaflet ; note the absence of 
 stomata. 
 
 Cut a vertical section of a leaflet at right angles to the 
 veins. Observe 
 
 g. On each side of the section the irregular epider- 
 mis, containing chlorophyll bodies. On a draw- 
 ing of the surface view of the epidermis draw 
 imaginary lines in various directions and note 
 the differing lengths of the lines across any cell. 
 This will explain the different lengths of the epi- 
 dermal cells cut by the razor. 
 
 //. Occasionally a stoma in the epidermis, bounded 
 by the two guard cells, communicating with an 
 intercellular space ; note the shape of the guard 
 cells. 
 
 2. Occupying the space between the upper and lower epi- 
 dermis, the loosely arranged irregular parenchyma of 
 
 * the leaf, mesophyll, also containing chlorophyll. 
 
 3. The large intercellular spaces of the parenchyma. 
 
 4. At intervals along the section the cut ends of the reins. 
 Identify the tissues with those seen in the stem. 
 
 5. Beneath the vein, forming a part of the lower surface 
 
120 MAIDEN-HAIR FERN. 
 
 of the leaf, will be seen three or four very thick-walled 
 cells. 
 
 6. Draw the vertical section of the leaf. 
 
 Bend a leaflet over the finger and cut the thinnest possi- 
 ble slice from the under surface lengthwise of the veins. 
 Mount with the cut surface upward, and note 
 
 7. The length of the cells over the veins and the manner 
 of overlapping, fibrous tissue, Draw. 
 
 8. The trichomes in the form of sporangia. Scrape some 
 sporangia from a sorus of a dried specimen, examine 
 dry with a low power, and note 
 
 a. The shape and color. 
 
 b. The row of brownish walled cells extending part 
 way around the sporangium, the annulus. 
 
 c. The stalk by which they were attached. 
 Examine with a high power sporangia from alcoholic 
 
 specimens, mounted in water with cover, and note 
 
 d. The structure of the wall of the sporangium. This 
 can be best studied in some of the immature spor- 
 angia which can usually be found in the same sorus 
 with the mature. Supplement this study by exam- 
 ining the wall of a bursted sporangium. Observe 
 that the wall consists of a single layer of much 
 flattened cells. Note the nuclei. 
 
 e. The annulus. Study the cells which compose it. 
 Notice that it forms a distinct ridge and is cpn- 
 tinued beyond the point where the cells are thick- 
 est by a series of short broad cells with thinner 
 walls. 
 
 /. The stalk ; the number of cell rows which com- 
 pose it and the absence of any trace of a fibro- 
 vascular bundle. 
 
ADI ANT UM PEDATUM. 12 1 
 
 g. Draw a sporangium. 
 
 //. The place of attachment. Scrape away most of 
 the sporangia from an indusium, mount it, and 
 notice the place of attachment of the remaining 
 sporangia and of the bases of the stalks of the 
 others. Observe its relation to the vein. 
 
 /. The mode of dehiscence. Tear off a bit of indu- 
 sium bearing a few sporangia, from a dried speci- 
 men previously soaked in water, place on a slip 
 without a cover glass and allow it to dry while 
 examining it with a low power, illuminating it 
 from above. Watch the process of bursting care- 
 fully. 
 
 j. The spores. In unbursted sporangia from alco- 
 holic specimens notice how closely they are 
 packed. Examine some which have escaped, 
 and note 
 
 Their shape and contents. 
 Their double walls. Burst some spores by 
 pressing on the cover. In favorable speci- 
 mens the outer layer of the wall, exospore, 
 will be ruptured and the delicate inner layer, 
 endospore, with its inclosed protoplasm will 
 be seen protruding. 
 
 D. THE PROTHALLIUM. Carefully brush away all the 
 dirt from the under side of a prothallium of medium size 
 and mount it with the under side uppermost. Examine 
 with a low power, and notice 
 
 1. The shape and the character of the margin. 
 
 2. The shapes of the cells. Draw a few cells of the 
 prothallium showing the various shapes. 
 
 3. The abundant chlorophyll bodies. 
 
122 MAIDEN-HAIR FERN. 
 
 4. The absence of fibro-vascular bundles. 
 
 5. The trichomes in the form of hairs of various 
 kinds. 
 
 a. Shorter or longer pointed hairs on the surface 
 and margin." 
 
 b. Short blunt hairs in like positions. 
 
 c. Rhizoids. Note 
 
 i. Their various sizes and lengths, 
 ii. The irregular shape. Draw. 
 
 6. Roundish bodies of considerable size near and 
 among the rhizoids, the sexual organs. 
 
 Examine with a high power, and notice the two sorts : 
 
 a. Some bodies spherical and filled with smaller 
 cells, the antheridia. Observe 
 
 i. The single layer of cells forming a wall la 
 
 which incloses 
 
 ii. A cluster of spherical cells, the sperm cells. 13 
 iii. If fresh material is being used, some mature 
 antheridia will probably have been ruptured 
 in mounting and the sperm cells with their 
 antherozoids have escaped. Note the movements 
 of the antherozoids after they have escaped 
 from the sperm cells. Kill them by treating 
 with iodine, watching them as they come 
 under its influence. Take note of the body of 
 the antherozoid, a spirally coiled filament to 
 which is usually attached an almost empty 
 
 11 Sometimes wanting. 
 
 12 Best seen in immature antheridia. All stages may usually be found 
 on the same prothallium. 
 
 13 If the structure of the antheridia can not be made out easily here, 
 postpone the study till D, 8. a. is reached. 
 
ADIAXTTM PEDATUM. 123 
 
 vesicle, and of the numerous cilia l4 at the free 
 end of the body. Draw. 
 
 iv. If no fresh prothallia are procurable the 
 
 antherozoid may be seen within the sperm 
 
 cell in alcoholic specimens, but its parts are 
 
 not distinguishable. 
 
 v. Draw both young and mature antheridia, 
 
 showing structure and contents. 
 
 />. Some bodies, of similar shape to antheridia but 
 apparently composed of four cells either quadrant- 
 shaped and meeting in the middle or somewhat 
 oval leaving a squarish space between them, the 
 archegomd, 
 
 \. In favorable fresh specimens one or more 
 moving antherozoids may be seen in the 
 space, canal, between the four cells. 
 Cut several vertical sections of the prothallium, passing 
 through the region of the notch and the cluster of rhizoids. 
 Treat with potash, examine with a high power, and notice 
 
 7. The number of cells in thickness of various parts 
 of the prothallium ; especially its rapid thickening in 
 the region of the rhizoids. 
 
 8. The sexual organs. 1 * 
 
 a. The globular antJieridia, wholly superficial. 
 
 Notice the thickness of the wall in mature and 
 
 immature ones. 
 /'. The archegonia may be recognized by the more 
 
 or less recurved projecting neck composed of 
 
 several rows of cells. Note 
 
 14 Difficult to see. Use ^th or higher objective if possible. 
 
 15 If their structure has not been comprehended before, it may be easily 
 made out now by examining numerous sections of the prothallium. 
 
1 24 MAIDEN-HAIR, FERN. 
 
 i. The number of rows of cells composing the 
 neck. 
 
 ii. The canal between the cells of the neck, and 
 extending from its apex to the imbedded 
 portion of the archegonium. This canal is 
 difficult to distinguish unless it contains a 
 granular substance. 
 
 iii. The cluster of cells at the base of the neck 
 imbedded in the prothallium, the body of the 
 archegonium. 
 
 iv. At the inner end (base) of the canal, in the 
 midst of the cells of the body, a single large 
 central cell, filled with a rounded mass of pro- 
 toplasm, the oosphere. 
 
 v. Draw the archegonium. 
 
 ANNOTATIONS. 
 
 Regarding only the position of organs, perhaps the 
 most striking difference between Adiantum and Atri- 
 chum is to be found in the fact that the former has its 
 leaves only above the ground, while the real stem is 
 buried below it. In contrast with those low plants 
 whose rhizoids have served them well enough for hold- 
 fasts, the fern has developed strong fibrous roots which 
 ramify widely and perform this office, assisted by the 
 buried stem. These roots are made necessary not 
 only by its greater stature and the consequently greater 
 strains, but by the necessity of wider foraging for the 
 supply of food. The roots must push their way 
 among the particles of soil, and, to protect the tender 
 tissues of the growing point, the tip of the root is 
 covered by a cap of cells, which arise from segments 
 cut off from the outer face of the tetrahedral apical cell. 
 
ADIAXTTM Fl-DATl'M. 125 
 
 As the cap is gradually disorganized and worn away by 
 contact with the soil it is replaced by new growth from 
 behind. The root cap is to be considered as a modified 
 and augmented portion of the epidermis. 16 
 
 Provision for continued growth of the stem in 
 length is found in the bud at its apex. The dying 
 base, however, follows with equal pace the advancing 
 apex, severing the lateral branches as it reaches them, 
 which thus become independent plants. 
 
 One of the most marked advances upon the structure 
 of the moss is to be found in "the development of an 
 extensive and complicated fibro-vascular system. The 
 simple leaf traces of Atrichum are here replaced by 
 better developed groups of fibers and vessels to which 
 the term fibro-vascular bundle is applied. These 
 bundles are distributed to every part of the plant ; con- 
 densed in those parts requiring strength, such as the 
 roots, stem and leafstalk ; diffusely branched in the 
 leaflets for the support of the chlorophyll-bearing 
 tissue. Branches of the fibro-vascular bundles having 
 once been formed, do not reunite with their fellows, 
 either as a whole or by anastomosing branchlets. The 
 only organs of Adiantum not reached by the fibro- 
 vascular bundles are the numerous and unusually 
 varied trichomes. These are developed as scales 
 thickly clothing the stem and base of the leaf stalk, as 
 hairs matted together about the roots, and as sporan- 
 gia crowded under the edges of the leaflets. 
 
 In the growing parts of all organs of the fern, the 
 cells are parenchymatous, but certain groups early dif- 
 
 16 Bessey, Botany, p. 163. 
 
126 MAIDEN-HAIR FERN. 
 
 ferentiate into the tissues which compose and surround 
 the fibro-vascular bundles. These tissues are quite dis- 
 tinct from each other as well as from the original 
 parenchyma. 
 
 The sheath which incloses the bundles does not 
 belong to the bundle itself, either in the fern or other 
 plants, but to the surrounding parenchyma. 
 
 The apparently perforated plates on the walls of the 
 sieve cells can not be seen clearly because of the layer 
 of protoplasmoid substance which adheres to the walls. 
 The perforations themselves are not easily demon- 
 strated though DeBary " thinks he has seen fine fila- 
 ments connecting granules on opposite sides of a plate. 
 The continuity of protoplasm between other than 
 sieve-cells has been demonstrated in many plants. 
 
 The arrangement of the tissues of the bundles in 
 stems and roots is of different types. In the former, 
 the phloem of the bundle encircles the xylem whence 
 it is known as a concentric bundle. In the latter, 
 the xylem forms a plate dividing the phloem into 
 two portions' which stand one on each side of it. 
 Assuming a center, the xylem and phloem masses are 
 symmetrically disposed about it, whence the bundle is 
 known as radial. 18 
 
 The root-bundle contains a tissue, the pericambium, 
 whose cells are still capable of division ; no such 
 tissue is found in the stem-bundles. New roots have 
 their origin not in the pericambium as in phanerogams, 
 but from cells of the bundle-sheath. 19 
 
 17 Comparative Anatomy, p. 181. 
 
 18 Cf. Strasburger, Das botanische Practicum, p. 209 ; DeBary, Com- 
 parative Anatomy, p. 362. 
 
 19 Cf. Strasburger, Das botanische Practicum, p. 276 ; Prantl and 
 Vines, Text-book of Botany, p. 51. 
 
ADIAXTL\M PEDATL'M. 127 
 
 The original parenchyma outside the bundles of the 
 stem early thickens its walls. These thick walls con- 
 sist of several layers, the most prominent of which, the 
 median, is called the middle lamella. This layer, 
 according to Strasburger 30 and others, is the primary 
 cell wall, upon which thickening layers are deposited. 
 By other histologists it is held that the layers are 
 formed, as the thickening progresses, by the differenti- 
 ation of the wall. Growth in thickness, according to 
 the first view, is due to apposition ; according to the 
 second, to intussusception. 
 
 The thickening layers of the wall are perforated by 
 numerous pits, through which probably pass threads of 
 protoplasm, not occupying the breadth of the pit, but 
 passing through much more minute openings in the 
 closing membrane of the middle lamella." 
 
 In addition to serving to increase the strength of 
 the stem, the cortical part is a convenient storehouse 
 for reserves of food, as indicated by the quantity of 
 starch in its cells. 
 
 The several cell layers of the leaf necessitate some 
 arrangement for allowing the entrance of gaseous food 
 and exit of the by-products of the cells' activity ; 
 hence the loose arrangement of the cells of the leaf, 
 forming' large intercellular spaces, which communicate 
 with the exterior by numerous stomata. The stomata 
 have here the form usual among the higher pteri- 
 dophytes and flowering plants, an elliptical slit, bounded 
 by two crescentic cells, which by their change of posi- 
 
 90 Bauund Wachsthum der Zellhaute, p. 175. 
 
 Sl Cf. Schaarschmidt, Protoplasm, Nature, xxxi, p. 290 ; Gardiner, 
 ibid, p. 390. 
 
128 MAIDEN-HAIR FERN. 
 
 tion may either open more widely or almost close the 
 orifice. 
 
 The prothallium, which is developed from a spore 
 produced by the leaf, bears little resemblance to the 
 mature spore-bearing fern plant. In its flattened shape, 
 cellular structure and rhizoids it does, however, have a 
 striking resemblance to the thalloid stem of Mar- 
 chantia. 
 
 There are thus two distinct stages in the life history 
 of the fern : one is known as the vegetative, asexual or 
 pteridoid stage, in which the plant consists of stem, 
 roots and leaves, and produces spores, and, strangely 
 enough, answers to the sporogonium of the moss ; 
 the other, known as the reproductive, sexual or thal- 
 loid stage, 22 in which the plant consists of a prothal- 
 lium, on which the reproductive organs are borne, and 
 corresponds to the leafy plant in the moss. 
 
 These reproductive organs are quite like those of 
 Marchantia and Atrichum. The antheridia consist 
 originally of one cell, which is later cut up into a cen- 
 tral cell and several parietal ones. The contents of 
 the central cell are divided into a number of small 
 spherical cells in which are formed the antherozoids. 
 When these are mature the parietal cells absorb water 
 and burst the apical one, thus permitting the anther- 
 ozoids to escape. The body of the antherozoid accord- 
 ing to Strasburger 23 is to be regarded as the proto- 
 plasm of the nucleus of the sperm cell, and the cilia as 
 
 22 Pteridoid and thalloid are terms introduced by Underwood, Our 
 native ferns and their allies, p. 35. 
 
 23 Das botanische Practicum, p. 455 ; Sachs, Text book, 2nd Eng. 
 ed., p. 423. 
 
ADIANTUM PEDATUM. 129 
 
 the peripheral protoplasm of the cell. The vesicle 
 attached to the hinder coils of the body is formed from 
 the central or intermediate contents of the sperm cell, 
 and usually contains some starch grains. 
 
 The archegonium is likewise originally a single cell 
 of the prothallium, which by subsequent division forms 
 a central cell containing the oosphere, the two canal 
 cells whose destruction results in the formation of the 
 canal, the four rows of neck cells and the layer of cells 
 immediately surrounding the central cell. ** 
 
 The conversion of the two canal cells into mucilage, 
 and the partial expulsion of this from the canal, 
 entangles and allows the entrance of the antherozoids, 
 which by their active movements work their way to 
 the base of the canal and penetrate the wall of the 
 central cell in which lies the oosphere. One anthero- 
 zoid bores its anterior end into the germinal spot of 
 the oosphere and disappears within it, probably reach- 
 ing the nucleus. The others lie for some time upon 
 the oosphere and are gradually absorbed, only one 
 antherozoid actually penetrating it. 25 
 
 The result of the fertilization of the oosphere is the 
 formation of a new plant, which remains attached to 
 the prothallium on its under side for some time. As 
 the young fern gradually spreads sufficiently, and is 
 able by means of its leaf and root surface to gather 
 nourishment for itself, the prothallium, no longer use- 
 ful, perishes. 
 
 84 Cf. Sachs, I.e. 
 
 * 5 Strasburger, op. cit., p. 458. 
 
SCOTCH PINE. 
 
 Pinus sylvestris L. 
 
 
 
 PRELIMINARY. 
 
 THE Scotch pine is a species commonly planted for 
 ornament. It may be readily recognized by the follow- 
 ing characters. At a short distance the tree has a 
 grayish-green color. The leaves are in pairs, five to 
 ten centimeters (two to four inches) long, somewhat 
 twisted, covered with a whitish powder which can be 
 rubbed off with the fingers and to which the peculiar 
 color of the tree is due. The cones are small, about 
 five centimeters (two inches) in length, the free ends of 
 the scales being produced into conspicuous protuber- 
 ances, which near the base of the cone are recurved. 
 
 The Austrian pine, a two-leaved species also com- 
 monly planted for ornament, differs from the preced- 
 ing in having longer leaves from ten to fifteen centi- 
 meters (four to six inches) in length with a dark green 
 color without any of the powder. The cones are much 
 larger and without the recurved protuberances. If 
 the Scotch pine can not be procured the Austrian will 
 do quite well, being closely similar to it in structure. 
 
 The flowers, both male and female, should be col- 
 lected in spring as soon as the male flowers begin to 
 scatter their pollen. The male flowers when mature 
 
PIN us s j v i /: s TRIS. 1 3 1 
 
 form conspicuous yellow clusters at the base of the 
 young shoots. The female flowers are quite inconspic- 
 uous, in small oval clusters of a pinkish color, project- 
 ing slightly beyond the ends of the young shoots. 
 The tree bearing abundant male flowers usually bears 
 few female ones, and vice versa. These flowers when 
 collected should be preserved in alcohol. A few weeks 
 later the two-year-old cones, which will be found just 
 below the new shoots, should be collected and pre- 
 served in alcohol. If the plant is to be studied in 
 spring or summer, some of the large terminal buds 
 should be collected in the late autumn, winter or early 
 spring preceding, and preserved in alcohol. Leaves and 
 stems should be gathered about the first of July, and 
 preserved in alcohol. Mature cones should be gathered 
 in winter or early spring and allowed to dry, care being 
 taken to prevent losing the seeds, which will shake out 
 on drying. 
 
 Fresh leaves and stems may be used for the study 
 of the gross anatomy, but if used for the minute 
 anatomy it is well before cutting sections to place them 
 in alcohol for a few days to get rid of the resin which 
 exudes and gums the fingers and knife unpleasantly. 
 Before cutting sections of stems or leaves which have 
 been preserved in alcohol and before dissecting the male 
 and female flower clusters, it is well to place them for 
 a day in a mixture of equal parts of alcohol and 
 glycerine, which renders them somewhat easier to 
 manipulate. They may, however, be used direct from 
 the alcohol. 
 
 The requisites for the complete study are stems, 
 
f.J2 SCOTCH PINE. 
 
 leaves, terminal buds, male and female flowers, year- 
 old and two-year-old cones, preserved in alcohol ; 
 mature cones and seeds, dry ; alcohol ; potash ; glycer- 
 ine ; sulphuric acid ; and if convenient, magenta ; 
 methyl blue ; and chlor-iodide of zinc. 
 
 LABORATORY WORK. 
 GROSS ANATOMY. 
 
 A. GENERAL CHARACTERS. Note 
 
 1. The central axis or stem; its few main branches and 
 numerous very short dwarf branches * bearing 
 
 2. Pairs of very slender elongated green needle leaves, 
 
 3. The scales upon the stem, those covering the buds at 
 the apex of the stem and those overlapping the bases of 
 young leaves. All may be called scale leaves. 
 
 4. Near the base of the young shoots in some specimens, 
 a number of oblong (nearly globular) clusters of light 
 yellow bodies, stamens, the male flowers ; in other 
 specimens, one or two small oval clusters of female 
 flowers, projecting beyond the end of the stem. 
 
 B. THE STEM. Examine 
 
 1. The surface of a year-old shoot. Note the scales 
 covering it, especially near the base of the shoot. 
 Compare with the surface of older stems ; note the 
 gradual obliteration of the scales. 
 
 2. The arrangement of the main brnches? Note the 
 
 1 The terms " dwarf branches " or "dwarf shoots" will be used to 
 distinguish these from the main branches or shoots. (The term shoot 
 includes the branch with its leaves.) 
 
 2 Best seen in specime'ns from young vigorous trees. If possible the 
 student should study the tree itself. 
 
PIN US SYLVESTRIS. 133 
 
 number of branches and the relative vigor of terminal 
 and lateral*shoots. Compare also, as to size, the buds 
 found in clusters at the apices of the branches. 
 
 The arrangement of the dwarf branches. Select the 
 straightest and most vigorous year-old branches for 
 this study. Notice 
 
 a. The position of the branches relative to the scales. 
 It. Their absence from certain portions of the stem. 
 
 c. Pull out the pairs of leaves from fifteen or twenty 
 consecutive branches. Stick a pin at the base of 
 any branch, and then find a branch that stands 
 directly above this one. Count the number of 
 branches between these, including the first. This 
 number will be equal to the number of vertical 
 ranks in which the branches stand. 
 
 d. Make a diagram in the following manner, to show 
 the relative position of the branches : draw lightly 
 a number of concentric circles about three milli- 
 meters apart (the number should be twice as 
 many as the number of vertical ranks, plus one). 
 Divide the outer circle by as many equidistant 
 points as there are vertical ranks of branches. 
 From these points draw radii, lightly. Take a 
 piece of straight stem about ten centimeters long 
 which has been stripped of its leaves. Mark the 
 position of three or four consecutive branches by 
 pins, so placed that if pressed in they would pass 
 through the center of the stem. Fasten the lowest 
 pin securely. Make a mark on the outer circle at 
 any radius to indicate the position of the branch 
 marked by the lowest pin. Erect the stem at 
 the center of the circles, making the lowest pin 
 coincide with this radius, and mark the next 
 
IJ4 SCOTCH PINE. 
 
 higher branch on the second circle at the radius 
 with which its pin now most nearly coincides. Mark 
 the third and fourth in the same way. Leaving 
 the lowest pin in place, move the pin next lowest to 
 the next higher unmarked branch, and mark its 
 position. Repeat this until all the circles are 
 filled, numbering each branch from the lowest up. 
 Studying this diagram determine 
 i. The arithmetical difference between the numbers 
 of the branches which lie on the same radius, 
 ii. The ^number of turns made by a spiral line 
 joining successive branches, i, 2, 3, 4, etc., 
 until it reaches a branch over the first, 
 iii. Find a fraction which will express the part of 
 a circle intervening between any two suc- 
 cessive branches. 
 
 iv. Note that the numerator of this fraction ex- 
 presses the number of turns made by the spiral 
 line, and the denominator the number of ranks 
 in which the leaves stand. 
 
 4. The buds. Notice 
 
 a. Their position and relative size. 
 
 b. Their shape. 
 
 c. Their structure. Study 
 
 i. The scales. Carefully strip them from the bud 
 with needles. Note particularly the character 
 of the edges and the differences between the 
 apical and basal portions. After removing the 
 brown apical portion, the green basal parts 
 will be seen closely investing 
 
 ii. The axis. Bisect longitudinally the portion 
 of the bud remaining. Observe in the center 
 the whitish stem or axis, tapering gradually 
 
FIX US S YL VESTRIS. 135 
 
 and then rapidly to a point, and bearing the 
 thick-set bases of the bud scales, in the axils 
 of which may be seen 
 
 iii. Secondary buJs? Take out one of these buds 
 carefully and dissect it. Note the scales which 
 cover it. By cautiously removing these the 
 rudimentary nccdle-lcares, looking like two 
 minute knobs, may be found, apparently at 
 the end of a very short stem to which the 
 scales were attached. 
 
 iv. Make drawings showing the external appear- 
 ance and structure of the buds, both main 
 and secondary. 
 d. Compare the buds with the branches. Observe 
 
 that a bud is simply an undeveloped branch. 
 
 5. The structure. Cut an old stem square across to study 
 the cut surface. Mount also a transverse section of 
 the same. Notice 
 
 a. A central yellowish or brownish spot of irregular 
 outline, the pith. 
 
 b. Surrounding the pith a zone of firm tissue, the 
 wood. Observe 
 
 i. The concentric masses of tissue, growth rings, 
 the number depending upon the age of the 
 shoot at the point cut. In thin parts of the 
 section, notice the difference between the 
 central and peripheral portions of any growth 
 ring, 
 ii. The many fine radiating lines, the medullary 
 
 rays. Note the extent of the larger ones, 
 iii. Many small scattered openings, the resin ducts. 
 
 3 These can only be found of sufficient size to dissect in buds collected 
 late in autumn or in early spring just before they begin to expand. 
 
I3 6 SCOTCH PINE. 
 
 iv. In some sections one or more distinct whitish 
 bundles passing out from the center of the 
 stem. Notice that a continuation of the cen- 
 tral pith occupies the center of each. Observe 
 the relation of these bundles to the scars on 
 the bark indicating the position of former 
 dwarf shoots. If the stem be four or more 
 years old, note that the bundles stop quite 
 abruptly at the close of the second year's 
 growth. 
 
 c. All the part outside the wood, the bark. Distin- 
 guish its three layers : 
 
 i. The inner fibrous layer, whitish. Notice its 
 appearance and thickness relative to the 
 whole bark. 
 
 ii. The middle, green layer. Notice the large 
 resin ducts. (In fresh specimens note the 
 color, consistence and odor of the liquid they 
 exude.) Compare the thickness of this layer 
 with that of the first. 
 
 iii. The outer brownish layer, except in quite old 
 stems made by the adherence of the bases of 
 the scale leaves. Note its relative thickness, 
 iv. Strip off a portion of the bark. The three 
 layers may be easily separated with the 
 fingers. Study the characteristics of each. 
 
 d. Bisect the stem longitudinally. On the cut sur- 
 face and in thin sections make out the pith, wood 
 and bark ; the growth rings, medullary rays, and 
 bundles extending toward bases of former leaf- 
 branches, in the wood ; the three layers of the bark. 
 
 e. Make drawings of the transverse and longitudinal 
 sections to show completely the structure of the 
 stem. 
 
PINUS SYL VESTRIS. 137 
 
 6. The dwarf shoots. Carefully break one from the stem, 
 and note 
 
 a. The scales (scale leaves) enwrapping it and the 
 bases of the needle leaves. If possible compare 
 these scales on young and old dwarf shoots. 
 
 It. The length. 
 
 c. The very small rudimentary terminal bud between 
 the leaves. This is best seen on the dwarf shoots 
 from young vigorous trees. It is minute or 
 absent on others. 
 
 C. THE LEAVES. 
 
 1. The scale leaves. These have already been studied as 
 they occur on the dwarf shoots (B. 6. a.) and in the bud 
 (B. 4. c. i.). Compare the scales of the stem with those of 
 a young bud and notice the loss of the deciduous apex. 
 
 2. The needle leaves. Note 
 
 The number on each dwarf branch. 
 The shape and apex ; also the shape of the trans- 
 verse section. Draw a leaf. 
 
 c. The color. Compare old and young leaves if 
 possible. 
 
 d. The texture ; firmest near the apex, softer near 
 the base, due to basal growth. These points 
 are especially noticeable in young leaves. 
 
 e. The edges. Draw the finger from the apex toward 
 the base. Examine with a lens. 
 
 /. The surface. Observe 
 
 i. That it is faintly whitened (glaucous) by a 
 powder which can be removed by drawing the 
 leaf through the fingers ; best seen on the 
 flat side. 
 
138 SCOTCH PINE. 
 
 ii. The longitudinal rows of whitish dots on both 
 surfaces. Cut a thin slice from the convex 
 surface, mount, and examine by transmitted 
 light. If sufficiently thin, the dots will now 
 be seen to be minute openings, the stomata or 
 breathing pores. 4 
 
 g. The structure. Cut a transverse section and 
 examine by transmitted light. Notice 
 i. Occupying the center an oval patch of whit- 
 ish tissue, the fibro-vascular region. 
 ii. Outside the central whitish area, compact 
 green tissue, mesophyll. In this zone notice a 
 dozen or more openings, the resin ducts. 
 iii. Enveloping the whole, the narrow colorless 
 
 cortical area. 
 iv. Draw the section. 
 
 Cut a longitudinal section parallel to the flat side. Make 
 out the same regions as in the transverse section. 
 
 D. THE FLOWERS. 
 
 i. Male or staminate. Carefully break off one of the 
 clusters. 
 
 a. Note the short stalk by which it was attached to 
 the stem. 
 
 b. Note that the cluster is made up of numerous 
 short-stalked bodies, the stamens, attached to an 
 axis. Each stamen consists of a flat scale bearing 
 on the inferior surface two enlargements, the 
 pollen sacs. 
 
 c. Burst a pollen sac. Note the innumerable minute 
 grains of pollen which escape. 
 
 4 More accurately, the external chambers of the stomata, for the real 
 stomata are deep seated. 
 
PIN US SYL VESTRIS. 1 30 
 
 d. Find a stamen which has burst spontaneously. 
 Note how it is ruptured (by slits). 
 
 e. Note the arrangement of the flowers? They are 
 almost sessile and crowded on an elongated axis 
 forming a spike. Notice the scale subtending 
 each flower, and the number and position of the 
 scales attached to the short stalk of the flower. 
 
 f. Note \h& position of the flowers ; each replaces a 
 branch on the young shoot. 
 
 g. Draw a stamen showing its structure. 
 
 2. Female or pistillate. Taking a single cluster, a spike, 
 notice 
 
 a. The stalk, peduncle, by which it is attached ; its 
 
 direction ; the scales on the peduncle. 
 />. That it is composed of two kinds of scales : (i) 
 
 thin, the bracts ; (2) thick, the carpellary scales. 
 Dissect out a single bract ; note 
 i. The texture and shape. 
 ii. Draw the bract. 
 
 Dissect out a single carpellary scale ; note 
 iii. The shape and texture. 
 iv. The prominent keel on the upper surface in 
 
 the median line. 
 
 v. Two enlargements on the superior surface, 
 near the proximal end, the ovules. Notice 
 Disposition of the ovules and the large ori- 
 fice at their free ends, the micropyle, the 
 integument of the ovule being prolonged into 
 a short tube, whose right and left sides are 
 still further produced into two short fila- 
 ments. 
 
 5 It is assumed that each cluster of stamens constitutes a single flower. 
 
140 SCOTCH PINE. 
 
 vi. Draw a scale showing all these points. 
 
 c. Difference in the size of bracts and scales in differ- 
 ent parts of the same cluster. 
 
 d. Position of the cluster ; replacing one of the 
 main branches. 
 
 Examine a year-old cone. Bisect it vertically, and note 
 
 e. The central tapering axis. 
 
 f. The cut edges of the scales and bracts. Observe 
 the relative thickness of the scales at their proxi- 
 mal and distal ends. 
 
 g. The ovules appearing in section at the base of the 
 scales. 
 
 h. Whether the scales are free from each other or 
 adherent. 
 
 /. Draw the cut surface. 
 
 Dissect out a scale with its ovules. Notice the many scales 
 with abortive ovules. Bisect a well developed ovule care- 
 fully, through the micropyle. Note 
 
 j. The diminished size of the micropyle. 
 
 k. The single integument. 
 
 I. That portion inclosed by the integument, the 
 nucellus. 
 
 m. Nearest the base of the nucellus (the end nearest 
 the micropyle being considered the apex) a large 
 cavity, the embryo-sac, partially or wholly filled 
 with a soft substance, the endosperm. 
 
 . Draw the cut surface of the ovule. 
 
 E. THE FRUIT (CONES). Examining a mature cone, 
 notice 
 
 1. The large carpellary scales, making the bulk of the cone. 
 Observe their color, above and below, consistence, shape 
 and markings at the free ends. 
 
 2. In an open cone, or by cutting away the basal third of 
 
PIN US S YL VESTRIS. 1 4 1 
 
 a closed cone, the smaller bracts subtending the carpel- 
 lary scales. 
 
 Closely applied to the superior surface of the carpellary 
 scales, a pair of thin wing-like scales, each bearing at its 
 proximal end a perfect seed or an abortive oi'ule. 
 
 The seed. Note 
 
 a. The shape, surface and markings. 
 
 b. At the pointed end notice the minute opening, the 
 micropyle. 
 
 c. The structure. Bisect the seed longitudinally par- 
 allel with the flatter faces, and in the halves make 
 out 
 
 The firm coat. 
 
 The inclosed portion consisting of two parts : 
 (i) the young plantlet, embryo, lying in the 
 axis ; (2) the food for the plantlet, endosperm.* 
 
 iii. Note the position of the embryo with respect 
 
 to the micropyle. 
 Take another seed and with needles dissect off 
 
 iv. The coat. Notice that it has differentiated 
 into two layers. Compare the two as to 
 color, thickness and strength. 
 
 Dissect the endosperm carefully from the embryo. In the 
 latter make out 
 
 v. The short stem, caulicle. 
 
 vi. The six divisions arising from about the apex 
 of the caulicle, the first leaves, cotyledons. 
 
 vii. A minute elevation in the midst of the coty- 
 ledons, at the apex of the caulicle, the rudi- 
 mentary terminal bud, plumule. (Not easily 
 seen.) 
 
 6 The endosperm has therefore entirely displaced jthe nucellus originally 
 surrounding it. (See D. 2. /. and m.) 
 
*4 2 SCOTCH PINE. 
 
 MINUTE ANATOMY. 
 
 A. THE STEM. Cut a transverse section of a year-old 
 stem, examine with a low power and note 
 
 1. The pith, occupying the center of the section. 
 Observe 
 
 a. The outline of the pith. 
 
 b. In some sections a portion extending outward to 
 enter a dwarf branch. The salient angles of the 
 pith are all due to such outward extensions at 
 different heights. 
 
 c. The loose arrangement of its cells. 
 
 2. The wood (xyleni). Observe 
 
 a. The arrangement of the cells. 
 
 b. The openings of the resin ducts. 
 
 c. The division into two zones, growth rings. 
 
 3. The cambium ; a narrow, cloudy looking zone, bound- 
 ing the xylem. (If the section be from a stem gathered 
 in winter or early spring, the cambium zone will be 
 indistinguishable.) 
 
 4. ^^ phloem ; of compactly-arranged cells, with a whitish 
 appearance. 
 
 5. The cortical parenchyma ; outside the phloem, consisting 
 of large, loosely-arranged cells, which in sections of a 
 fresh stem contain much chlorophyll. In this region 
 note the large oval openings of resin ducts. 
 
 6. Dark lines from the pith to the cortical parenchyma, 
 the medullary rays. 
 
 7. The edge of the section. The cortical parenchyma is 
 bounded by a row or two of small close-set cells. All 
 the tissue beyond this belongs to the bases of the scale 
 leaves, which cover the stem. 
 
SYLVESTRIS. 143 
 
 Examine with a high power and study 
 
 8. T\i& pith parenchyma. Note 
 
 a. The shape and arrangement of the cells ; the modified 
 
 shape of those passing out to a dwarf branch. 
 
 b. The contents. Test with iodine. 
 
 9. The xylem. Notice that the salient angles of the pith 
 divide it more or less completely into wedge-shaped 
 bundles. Studying one of these wedges, note 
 
 a. At the apex one or two resin ducts. Study their 
 structure, noticing 
 
 The shape of the opening. 
 The circle of rather delicate cells lining the 
 duct, the secreting layer. Note the granular 
 nucleus in each, nearly filling the cell. 
 iii. The quite irregular circle of flattened cells, 
 with longer diameters parallel with the circum- 
 ference, bounding the duct, the sheath. 
 
 b. Between the resin duct and the pith, forming the 
 point of the wedge, a group of several spiral and 
 reticulated vessels. These are rather difficult to 
 distinguish from the wood cells. They may be 
 recognized by their slightly thicker walls, the 
 smaller diameter and rounder shape of their 
 cavities. On staining the section slightly with 
 magenta, they take a somewhat deeper color than 
 the wood cells. After the section has lain for some 
 time in glycerine they may be recognized by their 
 greater opacity. 
 
 c. Forming the bulk of the xylem, the wood cells or 
 fibers. On account of the similarity of the mark- 
 ings (to be studied later) on their walls to those on 
 tracheae or vessels, they are called tracheides. 
 Note 
 
144 SCOTCH PINE. 
 
 \. Shape and arrangement. 
 ii. Their emptiness. 
 
 iii. Their thick walls, showing in thin parts of the 
 section, a middle lamella. 
 
 iv. In the thinnest part of the section, search for 
 places where the radial walls 7 of contiguous 
 cells bow away from each other like two watch 
 glasses placed with concavities together. 
 They are most readily found in the youngest 
 part of the xylem. In the most favorable 
 sections these bowed walls may be seen to be 
 interrupted at their points of greatest diverg- 
 ence thus -O-. These are sections of the 
 bordered pits (further described at A. 18. b. 
 
 iii.). 
 
 v. Compare the tracheides of the outer growth 
 ring with adjacent ones of the inner one. 
 
 vi. Wide one-sided bordered pits where the 
 tracheides adjoin the cells of the medullary 
 rays. 
 
 10. The cambium. Note 
 
 a. The radial rows of rectangular, 8 very thin-walled 
 cells, passing abruptly on the one hand into the 
 xylem, but shading almost imperceptibly on the 
 other into 
 
 11. The phloem. Note the two elements which compose 
 
 it : 
 
 a. Angular thick-walled cells with a whitish luster 
 and constituting the greater part of the phloem, 
 the sieve cells. In favorable sections the radial 
 
 7 7. e., those lying along a radius of the stem. 
 8 Very apt to be distorted in cutting. 
 
PIN US S YL VES TRIS. 1 45 
 
 walls of some of these cells will be found perfor- 
 ated by clusters of very fine pits, looking like 
 fine parallel lines passing across the wall. These 
 are sections of \htsieveplates; they occupy the 
 same relative position as the sections of the bor- 
 dered pits of the tracheides. Note the shape of 
 the sieve cells next the cambium and next the 
 cortical parenchyma. 
 
 />. Near the periphery of the sieve tissue an inter- 
 rupted row of cells with brown or yellow contents 
 in which are strongly refringent crystals. Near 
 the cambium a similar row of cells, larger and 
 rounder than the sieve cells and with colorless or 
 slightly yellowish homogeneous contents, in which 
 a small crystal or two may sometimes be seen. 
 These two broken rows of cells are \hz phloem- 
 parenchyma? 
 
 12. The cortical parenchyma. Note 
 
 a. The shape, size and arrangement of the cells. Com- 
 pare with pith parenchyma. 
 
 b. The contents. 
 
 c. The very large resin ducts. Compare their struct- 
 ure with those of the xylem (A. 9. a.). Note the 
 cells of the sheath, larger, thicker-walled and not 
 flattened as are those surrounding the ducts in the 
 xylem ; the secreting cells, similar to but more 
 numerous than those of the xylem ducts. 
 
 13. The medullary rays. In a thin part of the section 
 note 
 
 a. Their extent, from pith to cortical parenchyma. 
 
 9 Can be brought out by staining with chlor-iodide of zinc and better 
 still by methyl blue. 
 
146 SCOTCH PINE. 
 
 b. The shapes of the cells in the xylem and the grad- 
 ual transition into the cortical parenchyma. 
 
 c. The contents of the cells. 
 
 14. The bases of the scale leaves. (As they are closely 
 attached to the stem, and the lower portions not dis- 
 tinguishable from it, their transverse section is most 
 conveniently studied at this time.) Note the two 
 layers : 
 
 a. The inner ; cells very thin-walled and irregular, 
 apt to be distorted in cutting. 
 
 b. The outer ; composed of one or two rows of large 
 cells, sclerenchyma (note shape), and a single outer- 
 most row of smaller cells, the epidermis. Note 
 
 i. The thickening of the outermost wall of the 
 
 epidermis. 
 
 ii. The continuous layer covering this wall, the 
 cuticle. 
 
 15. Draw a part of the section, filling in sufficient to show 
 the structure completely. 
 
 Cut a longitudinal radial section of a year-old stem. 
 Examine with a low power, and make out 
 
 1 6. The same areas as seen in transverse section, in this 
 section appearing as strips : 
 
 a. The////? j its regular margins. 
 
 b. The xylem. Note 
 
 i. Patches* of transversely placed cells, the 
 
 medullary rays. 
 ii. The resin ducts j showing as one or two lighter 
 
 streaks in the xylem. 
 iii. The two growth rings. 
 
 c. The cambium ; a very narrow whitish strip. 
 
 d. 'The phloem ; compact and fibrous-looking. 
 
 e. The cortical parenchyma. 
 
PIN US SYL VESTRIS. 147 
 
 /. r ^\\t scale leaves. 
 Examine with a high power. Study 
 
 17. The pith cells. Note 
 
 a. The shape and arrangement. 
 
 1 8. The xylem. Note 
 
 a. Near the pith parenchyma a cluster of spiral and 
 reticulated vessels. Notice the irregularity and 
 closeness of the spiral thickening. 
 
 b. The tracheides, making the bulk of the xylem. 
 Note 
 
 i. Their shape. Observe their ends. 
 
 ii. Their thickened walls. 
 
 iii. Their markings, bordered pits. In the young- 
 est part of the xylem study the structure of one 
 of these pits. Observe the two concentric 
 circles they present. Note which is more dis- 
 tinct. Compare with transverse section and 
 discover the cause of this appearance. The 
 outer circle is at the point where, in section 
 (see diagram at A. 9. c. iv.) the arms of the 
 Y diverge from its stem ; the inner is the 
 edge of the opening in the bowed walls. By 
 examining this section thoroughly, chance 
 sections of the pits may be found which will 
 further elucidate their structure. 
 
 iv. The size of the pits compared with the breadth 
 of the fibers, and their arrangement on the 
 fibers. 
 
 v. The large thin spots on the walls of the cells 
 of the medullary rays, where they join the 
 adjacent tissues. 
 
 c. Between the tracheides and the spiral vessels a 
 few intermediate cells with plain pits nearly or 
 
148 SCOTCH PINE. 
 
 quite as large as the bordered ones of the trach- 
 eides. By focusing carefully the walls of these 
 cells may sometimes be seen in section. 
 
 19. The cambium. Note the shape and contents of the cells. 
 There is sometimes difficulty in discovering the end 
 walls of the cambium cells. It can be obviated some- 
 what by examining a section which has lain in glycerine 
 for a few hours. Notice particularly the delicacy of 
 the walls. 
 
 20. The sieve cells. Study 
 
 a. Their shape and arrangement. 
 
 b. The markings on their walls ; round or oval areas 
 of fine perforations, looking like minute specks. 
 Note their arrangement ; compare with that of the 
 bordered pits on the tracheides. 
 
 21. Thz phloem parenchyma ; note length and contents of 
 the cells. 10 
 
 22. The cortical parenchyma. 
 
 a. Study the shapes and contents of the cells. 
 
 b. Notice here and there cells which seem to have 
 been divided by a partition, the pair still retaining 
 an oval shape. 
 
 c. The large intercellular spaces. 
 
 23. The medullary rays. Study their cells in the cambium 
 and sieve cell regions. 
 
 24. The resin ducts. (Their longitudinal structure may be 
 studied either in the longitudinal or transverse section 
 of the stem, the latter usually showing a longitudinal 
 
 10 Difficult to distinguish without staining with methyl blue or chlor-io- 
 dide of zinc. 
 
PLVUS SYLVESTRIS. 149 
 
 section of one or more of the horizontal branches con- 
 necting neighboring ducts. The structure is most 
 easily made out in those of the xylem, those of the 
 phloem being too large to allow a complete section to 
 be easily obtained.) Note 
 
 a. The empty cells forming the sheath ; their shape. 
 
 b. The secreting parenchyma cells lining the duct ; 
 shape and contents. 
 
 25. The bases of the scale leaves. Note 
 
 a. The delicate thin-walled cells forming their inner 
 portion. 
 
 b. The rather thick-walled cells, sclerenchyma, form- 
 ing the outer part. 
 
 c. The very thick-walled outer row, the epidermis, 
 with thickly pitted walls. 
 
 d. The very thick cuticle. 
 
 e. The contents ; note color. 
 
 26. Draw a portion of the section, showing all the above 
 points. 
 
 Cut a longitudinal tangential section, passing through 
 the wood. Examine with a high power, and note 
 
 27. The cut ends of the medullary rays, wedged between 
 the fibers of the xylem. Notice 
 
 (7. The number of rows of cells in the thickness and 
 height of each ray. 
 
 b. The thin parts of the walls corresponding to the 
 pits (see A. 18. b. v.). 
 
 c. Make a drawing of one of the rays, showing also 
 a few adjacent tracheides. 
 
 28. The numerous sections, in different directions, through 
 bordered pits. Study these sections further, if necessary 
 to an understanding of the structure of the pits. 
 
150 SCOTCH PINE. 
 
 29. The very tapering ends of the tracheides. 
 
 Cut transverse and longitudinal sections of a young stem 
 collected at flowering time. Examine with a high power, 
 and compare with similar sections of the older stem. Notice 
 the walls and contents of the cells of the several tissues 
 and particularly 
 
 30. The distinctness of the spiral and reticulated vessels. 
 
 31. The deep indentations of the margin of the stem in 
 transverse section, marking the breadth of the scale 
 leaves. 
 
 32. The simple epidermal and hypodermal tissues consti- 
 tuting the bases of the scale leaves. 
 
 Strip off the brown apical portions of the bud-scales from 
 a winter bud and bisect it longitudinally a little to one side 
 of the center. Cut a series of longitudinal sections as uni- 
 formly thin as possible, until the center of the stem has been 
 passed. Mount every section, treat with potash and exam- 
 ine with a low power. Search for the section which 
 includes the center of the axis. It may be recognized by 
 the conical shape of the apex. Note 
 
 33. The central axis or stem.. Observe the arrangement 
 of the cells. 
 
 34. The buds on the side of this axis. Notice 
 
 a. The large scale (base of bud scale) subtending 
 each. . 
 
 b. The central rounded mass of cells, an undevel- 
 oped dwarf branch, covered in by scales. Search 
 for a bud whose central part shows three rounded 
 protuberances. These are the two leaves with the 
 terminal bud of the dwarf branch between them. 
 Draw. 
 
PIN US S YL VES THIS. 1 5 I 
 
 35. The conical apex, growing point, of the axis. Notice 
 the scales which cover it. 
 
 Examine with a high power. Study both the growing 
 leaves and the apex of the stem. Note 
 
 36. The shape of the cells, which in these regions are cap- 
 able of division and are collectively known as the 
 primary meristem. 
 
 37. A short distance behind the growing apex, the cells of 
 the primary meristem become differentiated, some 
 becoming elongated and fusiform and others forming 
 the spiral vessels. Trace them further and further from 
 the growing point and notice that the differentiation 
 constantly increases. 
 
 38. On the sides of the section, just behind the conical 
 point, one or two elevations, the apices of the axes of 
 lateral buds of the succeeding season. Draw the 
 apex. 
 
 B. THE LEAVES. Cut a transverse section of one of 
 the older needle leaves below the middle. Examine with a 
 low power, and note 
 
 1. The shape of the section. 
 
 2. The three distinct regions it presents : 
 
 a. The narrow outer cortical region, whitish in color. 
 
 b. The central oval fibro-vascular region, bounded by 
 a distinct chain of cells, the bundle sheath. 
 
 c. Between these two regions, a zone of green (green- 
 ish even in alcoholic specimens) parenchyma, the 
 mtsophyll. 
 
 3. The number and position of the resin ducts. 
 
 4. Make a sketch of the section. 
 
152 SCOTCH PINE. 
 
 Examine with a high power, and study 
 
 5. The epidermal cells. Note 
 
 a. The very thick walls, their cavities nearly or quite 
 obliterated. The outer layers of this thickening 
 are cuticularized. 
 
 b. The cuticle, quite thick and dipping as a thin 
 wedge between the cells. 
 
 c. The crack-like pits radiating from the cavity. 
 
 d. The enlargement of the cell which forms the corner 
 of the leaf. 
 
 e. The stomata. Study their structure carefully, 
 noting 
 
 i. The peculiar shape of the epidermal cells 
 above the stoma, the outer wall, about as 
 thick as the adjacent cells of the epidermis, 
 prolonged upward to form a ridge overarch- 
 ing the outer chamber of the stoma. Observe 
 the cavity of these cells, much larger than 
 those of adjacent cells. At the bottom of the 
 outer chamber, 
 
 ii. The guard cells, their shape and the thicken- 
 ing of their outer walls. 
 
 iii. The large intercellular space beneath the 
 guard cells, the inner chamber of the stoma. 
 
 6. The usually single, in places double or triple, row of 
 small cells underneath the epidermis, the hypoderma, 
 Note 
 
 a. The shape, and the thickness of walls. 
 
 b. Where the greatest number of cell-rows occurs. 
 
 c. The well-defined middle lamella. 
 
 d. That the hypoderma is interrupted at each stoma. 
 
 7. Draw a stoma with a few of the adjacent epidermal 
 and hypodermal cells. 
 
PIN US SYLVESTRIS. 153 
 
 8. The mesophyll. Note 
 
 a. The shape of the cells, and the number of rou>s 
 between the hypoderma and bundle sheath. 
 
 b. The infolJings of the wall, dividing the cavity 
 into recesses. Observe the position of the most 
 prominent of these infoldings in the outermost 
 row of mesophyll cells. Observe occasionally 
 (usually near a stoma) branched cells. Deter- 
 mine the relation of these to the cells with simple 
 infoldings. 
 
 c. In fresh specimens, the abundant chlorophyll. 
 
 d. The resin ducts ; compare their structure with 
 those of the stem. Notice the thick walls of the 
 cells of the sheath. 
 
 9. Draw a few mesophyll cells showing also a resin duct. 
 10. The fibro-vascular region. Study 
 
 a. The bundle sheath ; shape and contents of the 
 cells. 
 
 b. The two masses of small cells, the fibro-vascular 
 bundles, somewhat separated from each other and 
 obliquely placed. Note the well-marked division 
 into two areas : 
 
 i. The xylem, next the flat side of the leaf, 
 consisting of spiral and reticulated ves- 
 sels and tracheides, arranged in radial rows. 
 
 ii. The /&!, next the convex side of the leaf, 
 consisting chiefly of undeveloped sieve cells. 
 
 iii. The radial rows of parenchyma (like medul- 
 lary rays), passing through both xylem and 
 phloem. 
 
 iv. In the xylem area, occasionally a poorly 
 developed resin duct. 
 
154 SCOTCH PINE. 
 
 v. Draw one of the bundles. 
 
 c. Between the bundles and more or less encircling 
 them, especially next the convex side of the leaf, 
 fibrous tissue consisting of large thick-walled cells 
 with small cavities. 
 
 d. On the side of the bundle pair toward the flat 
 side of the leaf, large thin-walled, mostly empty cells. 
 
 e. Filling the remainder of the fibre-vascular region 
 and entirely encircling the parts named, large 
 tracheides resembling the preceding, but with more 
 or less conspicuous contents, and walls marked 
 with bordered pits. Compare the markings with 
 those of the tracheides of the stem, studying both 
 face and section views. 
 
 f. Draw a few cells of each tissue named outside the 
 bundles. 
 
 Cut a longitudinal section through the central part cf the 
 leaf. Examine with a high power, and study 
 
 11. The epidermis. Note 
 
 a. The shape of the cells. Unless the section be quite 
 thin, the epidermis will appear as a continuously 
 thickened border of the section. The end walls of 
 the cells are hard to make out, even in the best 
 sections. 
 
 b. The irregular cavity, and innumerable //& which 
 perforate the thickening layers. 
 
 c. If a number of sections be made, one or more will 
 traverse a line of stomata. Note the shape of 
 the outer chamber, the shape of the guard cells, 
 and of the intercellular space below. 
 
 d. Draw a stoma and the adjacent cells. 
 
 12. Underlying the epidermis, the elongated sclerenchyma 
 cells, the hypoderma. In sections passing through a 
 
PIN US S YL VESTRIS. 1 5 5 
 
 line of stomata, note the absence of any hypoderma, 
 except short cells between the guard cells of adjacent 
 stomata. 
 
 13. Draw a few cells of epidermis and hypoderma. 
 
 14. The mesophyll. Note how loosely it is arranged, with 
 an intercellular space between the rows of cells, enlarg- 
 ing under each stoma. Note also the shapes of the 
 cells, the apparent absence of infoldings in this view, 
 and the number of cells in each row between the bun- 
 dle sheath and hypoderma. The determination of the 
 latter point will need close inspection and careful 
 focusing. The infoldings seen in transverse section 
 are now seen as apparent partitions increasing the 
 apparent number of cells above the actual. In places 
 none of these false partitions occur, and the real number 
 of cells may be easily noted. Draw a few rows of meso- 
 phyll cells. 
 
 15. The resin ducts ; note the sheath cells, elongated and 
 thick walled ; the secreting cells, with thin wavy walls 
 and prominent nuclei. Draw. 
 
 1 6. The fibro-vascular region. The various tissues of this 
 region appear as strips in this section. 
 
 a. The bundle sheath ; a row of elongated cells next 
 the mesophyll. Draw. 
 
 If. The tracheides, on both sides of the bundles ; 
 note the shape and markings of the cells. 
 
 c. Note the change in shape where this tissue adjoins 
 the fibrous tissue, the cells becoming much elon- 
 gated. Draw, showing both forms. 
 
 J. The fibrous tissue ; greatly elongated thick-walled 
 fibers with tapering ends, next the tracheides. 
 Draw. 
 
156 SCOTCH PINE. 
 
 <?. Next the xylem, large thin-walled mostly empty 
 
 cells. 
 
 /. The phloem j consisting of thick-set, very long 
 cells, with slightly oblique ends, usually crowded 
 with protoplasm and containing large nuclei. 
 Draw. 
 g. The xylem j note 
 
 i. Tracheides like those of the stem but poorly 
 
 developed, with few markings, 
 ii. Spiral vessels like those of the stem ; var- 
 iously placed with respect to the tracheides. 
 Cut the thinnest possible slice from the surface of an old 
 leaf and then cut a thin section from the same place. 
 Mount both with the outer surfaces upward and examine 
 with a high power. Studying the first, the slice of epidermis, 
 note 
 
 17. The arrangement of the stomata. 
 
 18. The two kinds of epidermal cells, those lying near and 
 in a line of stomata and those lying between the lines 
 of stomata ; observe the shapes. In the former note 
 the ridge formed by the upturned edges of the six cells 
 which bound the stoma. 11 If this cannot be readily 
 made out, treat the specimen with potash and observe 
 again in a few minutes. Draw a few cells of each. 
 
 In the tangential section from beneath the epidermis, 
 note 
 
 19. The cut ends of the mesophyll cells ; shape and arange- 
 ment. Draw. 
 
 11 The student should not mistake the peripheral border of the ridge 
 for the outer wall of the six cells. The cells mentioned are quite large, 
 the central ones extending from one stoma to another and the others us- 
 ually half that distance. 
 
PIN US SYLVESTRIS. 157 
 
 20. The guard cells of the stomata also may usually be 
 seen. Draw. 
 
 Cut a transverse section of the base of a young leaf, col- 
 lected at flowering time. 
 
 21. Compare with the transverse section of an older leaf. 
 
 Note the presence of protoplasm in almost all the 
 tissues, completely filling the cells. Clear with potash. 
 Compare carefully each tissue with the mature form, 
 noticing particularly the lack of differentiation of the 
 tissues, especially in the fibre-vascular region. 
 
 Mount one of the scales which enwrap a young 
 leaf. Examine with a low power, and note 
 
 22. The shape and arrangement of the cells. 
 
 23. The fringe at the free end of the scale. Notice of 
 what each hair of the fringe consists. 
 
 Cut a transverse section of these scales by cutting a 
 transverse section at the base of a pair of young leaves. 
 The sections of the scales will float off when the leaf section 
 is placed in water. Note 
 
 24. The number of cell rows i-n thickness ; the shape of 
 the cells and thickness of the walls of some of them. 
 
 25. A trace of a fibro-vascular bundle in the center of some 
 of the thicker scales. 
 
 C. THE FLOWERS. 
 
 i. The stamens. Tease out a portion of the wall of an 
 empty pollen sac. Examine with a high power, and 
 note 
 
 a. The shape of the cells. 
 
 b. The beaded appearance of the walls. 
 
158 SCOTCH PINE. 
 
 c. Draw a few cells. 
 
 Place an entire male flower, from whose pollen sacs the 
 pollen has all escaped, between pieces of pith and cut trans- 
 verse sections of the cluster. Chance sections of the walls 
 of the pollen sac will thus be obtained. Examine with 
 a high power, and note 
 
 d. The number of cells in thickness. 
 
 e. The reticulated thickening of the lateral walls, 
 which gives rise to the beaded appearance seen in 
 the surface view. Draw. 
 
 Break open two or three pollen sacs and mount the 
 pollen. Examine with a high power, and note in each 
 grain 
 
 /. The three lobes into which it seems to be divided : 
 a central one, the essential part of the grain ; 
 attached to this two vesicular protrusions or wings 
 with wrinkled surfaces. 
 g. In the central lobe make out 
 
 i. The double wall of the cell ; the outer part, 
 the extine, rather thick and having its 
 slightly roughened external portion expanded 
 into the vesicular wings ; the inner, the inline, 
 very thick and transparent. 
 
 ii. The contents (treat with iodine) ; protoplasm, 
 abundant starch, and sometimes one or two 
 clear-looking drops of oil. 
 
 iii. The division into two cells : one very large, 
 containing the starch and oil ; the other very 
 small, at the end of the central lobe furthest 
 from the wings, best seen when the grain is 
 lying on its side. 
 
 Treat the iodine-stained pollen grains just examined with 
 75^ sulphuric acid. Press gently on the cover glass with 
 
7Y.V C'S SVL VESTRIS. 1 5 9 
 
 the handle of a dissecting needle. Examine with a high 
 power, and note 
 
 //. The empty extine, distorted by the pressure, and 
 
 stained yellow. 
 /. The intine, blue, much swollen, and either empty 
 
 or still containing the protoplasm, starch and 
 
 oil. If empty the smaller cell can usually be well 
 
 seen. 
 j. The yellow protoplasm, dark blue starch grains and 
 
 clear oil drops, escaped from some of the pollen 
 
 grains. 
 k. Draw a pollen grain, showing all its parts. 
 
 2. The cone. Take a cluster of female flowers, bisect it 
 longitudinally, and from one of the halves cut longi- 
 tudinal radial sections. Treat with potash. Examine 
 with a low power, and selecting a section which has 
 passed through an ovule, note 
 
 a. The central axis bearing the bracts, each subtend- 
 ing a carpellary scale, to whose upper surface the 
 oi'itle is attached. 
 
 />. The body of the ovule, nucellus, surrounded by 
 
 c. The integument, which is prolonged beyond it. 
 
 d. The continuity of the nucellus and integument 
 with the carpellary scale. 
 
 e. The orifice in the integument at its proximal end, 
 the micropyle. 
 
 f. Draw, showing the above points. 
 Examine with a high power, and notice 
 
 g. That the cells of the nucellus, integument and 
 scale are all alike parenchymatous and filled with 
 protoplasm. 
 
 Dissect out a carpellary scale from the central part of a 
 year-old cone and cut a series of longitudinal sections, 
 
160 SCOTCH PINE. 
 
 including about the middle third of the ovule. Mount all 
 the sections, and treat with potash. Examine with a low 
 power, and note 
 
 h. The /#/-$ of the ovule : integument, nucellus and 
 
 micropyle. 
 
 /*. The parts of the scale : the scale proper and the 
 wing of the seed. Notice that the tissues of the 
 scale are continuous with those of the wing and 
 ovule ; a faint trace of the coming lines of separa- 
 tion may however be detected. 
 
 / The differentiation of the tissues of the scale into 
 two kinds : the one of densely packed small cells 
 forming an outer layer with deeper seated fibers ; 
 the other of looser larger cells, forming the inter- 
 mediate portion. 
 
 k. The differentiation of the integument of the ovule 
 into two layers, the outer of densely packed small 
 cells, the inner of looser larger cells. 
 /. The discoloration of the apex of the nucellus. 
 /;/. The presence of a large cavity in the nucellus, the 
 embryo-sac, filled with a delicate transparent tissue, 
 endosperm. 
 Examine with a high power, and note 
 
 n. That the body of the nucellus is almost entirely 
 
 displaced by endosperm cells. 
 
 o. The wall of the embryo-sac ; wavy and usually 
 broken away from the remaining cells of the 
 nucellus in cutting the section. 
 /. The endosperm cells; observe 
 i. The delicacy of the walls. 
 ii. The contents ; thready protoplasm and a very 
 
 large round nucleus with a nucleolus. 
 iii. Draw a few endosperm cells. 
 
PI XL T S SYL VESTRIS. l6l 
 
 t/. Near the outer end " of the embryo-sac, one or two 
 much larger cells, the archegonia or corpuscula." 
 Observe the distinct row of endosperm cells, 
 smaller than the others, which surrounds the arche- 
 gonia. 
 
 r. Occasionally one or two pollen grains having 
 shed the extine, may be found in the micropyle, 
 and still more rarely, some may be found which 
 have begun to emit their tubes. 
 
 s. Make a diagram of the ovule and all its parts, 
 together with the wing and carpellary scale. 
 
 ANNOTATIONS. 
 
 The Scotch pine raises a strong tall stem above the 
 ground for the purpose of better exposing its leaves 
 and fruits to the air and sunlight. This habit is cor- 
 related with the excessive development of the fibro- 
 vascular system, which includes all the tissues of the 
 mature stem, with the exception of a trifling amount 
 at its center and circumference. 
 
 Not only is there provision for continued growth in 
 length by the formation of terminal buds, as in Adi- 
 antum, but there is also provision for growth in diameter. 
 A part of the tissue, from which the fibro-vascular 
 bundles are formed, lying between the xylem and 
 phloem, retains the power of division and by annual 
 increase in the number of cells, chiefly in a radial 
 direction, the thickness of the bundle is increased. The 
 difference in the size and shape of the cells added to 
 the xylem in the spring and autumn gives rise to the 
 
 12 /. e., the end nearest the micropyle. 
 
 13 Frequently not well developed at this time. 
 
1 62 SCOTCH PINE. 
 
 so-called annual or growth-rings which can be seen in 
 the wood. 
 
 The scales which cover the stem, though called by 
 the same name as the brown chaffy appendages to the 
 stem of the fern, are not trichomes like them, but 
 leaves. In addition to these scale leaves, which per- 
 form only slightly the function of true leaves, there 
 are the needle leaves, upon which the foliage work 
 chiefly depends. The delicate scales which enwrap 
 the bases of the needle leaves are not trichomes, but 
 leaves, as the rudimentary fibro-vascular bundle in 
 them shows. 
 
 The different mode of arrangement of the scale 
 leaves (and consequently of the dwarf branches) upon 
 the terminal and lateral shoots is worthy of notice. 
 
 Concerning the homology of the parts of the male 
 and female flowers, more especially the latter, there 
 has been and still is much controversy. It is gener- 
 ally admitted that each cluster of stamens constitutes a 
 single male flower. The scales which bear the pollen 
 sacs on their under sides are homologous with leaves, 
 as is shown by their position and anatomical characters 
 and occasionally in teratological changes. 14 Moreover, 
 the flower is subtended by a bract, and the floral axis 
 bears several (usually three) bractlets below the 
 stamens. 16 
 
 As first announced by Robert Brown le the ovule in 
 the pines and their allies is naked, /. e. it is not sur- 
 rounded, as in the vast majority of flowering plants, 
 
 14 Eichler, Blttthendiagramme, p. 59. 
 
 15 Cf. Strasburger, Das botanische Practicum, p. 469. 
 
 16 Appendix to Botany, Capt. King's Voyage, iv, p 103. 
 
PIN US S YL VESTRIS. 1 63 
 
 by an ovary ; whence the entire group of plants having 
 this character are called gymnosperms. Latterly, there 
 has been much controversy as to the nature of the 
 carpellary scale and whether the ovule is really or 
 only apparently naked. The latter question involves 
 the determination of the nature of the integument 
 of the ovule. It is held on the one hand that the 
 ovule consists of nothing but a nucellus, and that 
 the coat surrounding this nucellus is the homologue 
 of the wall of the ovary. On the other hand it is 
 contended that this structure is the true integu- 
 ment of the ovule and that the scale which bears 
 the ovule is an open carpel or pair of carpels. 17 In 
 the laboratory directions we have adopted the latter 
 view, calling the organ which bears the ovules a carpel- 
 lary scale. This carpellary scale is theoretically " com- 
 posed of two leaves of an arrested and transformed 
 branch from the axil of the bract, which are in the 
 normal manner transverse to the subtending bract, 
 : * * each bearing an ovule on its dorsal [as to 
 position, upper] face; the two are coalescent into one 
 by the union of their posterior edges, and the scale 
 thus formed is thus developed with dorsal face pre- 
 sented to the axis of the cone, the ventral to the bract. 
 It is therefore a compound open carpel composed of 
 two carpophylls. This character of being fructiferous 
 on the back or lower side of the leaf occurs in no other 
 phaenogamous plants." 18 
 
 11 References to extensive literature of this discussion may be found in 
 Gray, Struct. Bot., p. 272. For a general statement of views and 
 summing up of argument see Eichler, Sind die Coniferen gymnosperm 
 odernicht? Flora, 1873, p. 241. Consult also Sachs, Text-book, 2nd 
 Eng. ed., footnote, p. 507. From references in these places the whole 
 subject may be traced. 
 
 18 Gray, Struct. Bot., p. 273, footnote. 
 
164 SCOTCH PIN. 
 
 As soon as the male flowers begin to scatter their 
 pollen to the wind, the axis of the young cones elon- 
 gates, separating the carpellary scales sufficiently 
 to allow the pollen to be blown in between them, 
 and to slide down, guided by the keel, to the pro- 
 longations of the integument. These prolongations 
 subsequently roll inward, thus carrying any grains 
 which may have become attached to them to the apex 
 of the nucellus. After this process of pollination is 
 accomplished the bracts cease to develop and like- 
 wise the now useless keel. 19 
 
 The minute anatomy of the Scotch pine presents 
 many points of considerable interest. 
 
 True tracheary tissue is formed only at the peri- 
 phery of the pith, where a cluster of spiral, reticulated 
 and pitted vessels occurs at the apex of each woody 
 wedge. 
 
 The tissue of the wood is almost exclusively made 
 up of tracheides, on whose radial walls are bordered 
 pits. As these walls, originally thin and plain, increase 
 in thickness irregularly, a part of the thickening on 
 each side of the primary wall grows away from it 
 to form the arched " border " of the small aperture 
 which remains. For some time the primary wall 
 remains as a membrane separating the two cells ; 
 when finally this is destroyed there is free communica- 
 tion between the contiguous cells. 20 
 
 The thin delicate walls of the cambium allow great 
 activity of the contained protoplasm, which results 
 
 19 Strasburger, op. cit., p. 476. 
 
 20 Cf. Strasburger, Bau und Wachsthum der Zellhaute, p. 43, taf. 
 iii. For figures cf. Sachs, Text-book, p. 25. 
 
PIXUS S YL VESTR1S. 1 65 
 
 in the formation by division of many new cells. The 
 older cells on the axial side become gradually trans- 
 formed into the tracheides and those on the peripheral 
 side into the elements of the phloem. 
 
 Replacing the tracheides of the xylem are the sieve 
 cells of the phloem. The radial walls of the larger cells 
 have on them clusters of small perforations which are 
 known as sieve plates or disks. These sieve plates are 
 homologous with the bordered pits on the tracheides of 
 the xylem." At a little distance from the cambium 
 they become covered with a homogeneous substance, 
 the so-called callus plate, which completely interferes 
 with the function of the sieve cells. Though this callus 
 plate is subsequently dissolved, the sieve cells never 
 regain their activity, the protoplasm having by this 
 time disappeared from them. " 
 
 The cells with brown and crystalline contents are 
 the true phloem parenchyma. A single row of them 
 is formed each season, so that the age of the stem may 
 be determined by these, " as also by the growth rings 
 of the xylem. 
 
 The general arrangement of the tissues of the bun- 
 dles is in contrast to that in the fern. The xylem and 
 phloem here lie side by side, whence the bundle is 
 known as collateral. " 
 
 The rigidity of the leaves of the pine is due to the 
 thickening of the cells of the epidermis, together with 
 the development of the layer or layers of hypodermal 
 fibers. 
 
 21 Strasburger, Das botanische Practicum, p. 143. 
 
 2U Strasburger, op. cit., p. 147. 
 
 83 Strasburger, op. cit., p. 146. 
 
 94 Russow, Vergl. Untersuch., fide DeBary, Comp. Anat., p. 319. 
 
1 66 SCOTCH PINE. 
 
 Although the guard cells of the stomata appear at 
 first sight to be deeper seated than the epidermis, 
 observation teaches that they have been pushed down 
 by the crowding over them of the adjacent epidermal 
 cells, and here, as always, belong to the epidermis. 
 This is confirmed by examining younger stomata. 
 
 The partial partitions by which the mesophyll cells 
 are distinguished are explained by Sachs" as intru- 
 sive foldings due to local growth of the wall at the 
 point where the fold occurs. Corry 28 however asserts 
 that there is no real, but only apparent ingrowth, 
 which is caused in this way : when the cells are still 
 small their nuclei are attached to the protoplasm lining 
 the wall by delicate protoplasmic strands one or more 
 of which at a later period become converted into cel- 
 lulose thus attaching the nuclei firmly to the wall. 
 When the cell enlarges these points are firmly held 
 near the nucleus. Since some of the strands soon 
 break, many of the infoldings are shallow while others 
 holding, cause deep infolding. 27 The purpose of these 
 infoldings is considered by Haberlandt to be to 
 secure a greater surface on which to display the 
 chlorophyll bodies. Corry says of them : " They per- 
 form at all events a very obvious and noteworthy 
 function in forming the intercellular spaces beneath 
 the stomata in Pinus, and in producing air channels 
 
 25 Text-book, 2nd Eng. ed., p. 74. 
 
 26 On some points in the structure and development of the leaves of 
 Pinus sylvestris. Proc. Camb Phil. Soc., iv (1883), p. 344 et seq. 
 
 27 Similar infoldings in leaves of Elymus Canadensis and other grasses 
 are described by Kareltschikoff (Bull. Imp. Soc. Nat. Moscow, xlt 
 [1868], p. 180) and in Caltha palustris, Anemone nemorosa and a 
 number of other plants by Haberlandt (Oester. Bot. Zeit, xxx [1880], 
 P- 305). 
 
PIN US S YL VESTRIS. 1 6 7 
 
 between the cells forming the several rows of palisade 
 tissue." 28 
 
 The four bundles of each pair of leaves have the 
 normal orientation, the xylem portions all facing a 
 common center and the phloem the periphery. The 
 imbedding of the bundles in a mass of colorless tissue 
 surrounded by a sheath is common among the pines 
 and their allies. 
 
 In this central tissue many of the cells are tracheides 
 (see fig. 7), as pointed out in the laboratory part ; they 
 are arranged in a special manner and are characteristic 
 of ConiffTG* These tracheides during the activity 
 of the leaf contain water, 80 and hence have been, called 
 transfusion tissue by H. v. Mohl 31 and others. 
 
 The existence of occasional poorly developed resin 
 passages in the xylem of the leaf bundles is to be noted, 
 as it has been denied by Corry 33 and Van Tieghem. 33 
 (See fig. 7 r). 
 
 In comparing the reproduction of the pine with 
 that of the fern and earlier forms we find advances of 
 much interest. In the fern, as in the moss and liver- 
 wort, the spore grows into a structure, which bears 
 the reproductive organs. In the moss and liver- 
 wort this sexual or thalloid stage comprises by far the 
 larger part of the life cycle, while the asexual stage 
 (the so-called fruit) is small and quite unable to lead 
 an independent existence. In the fern the thalloid 
 
 88 Op. cit., p. 355. 
 
 * 9 Cf. DeBary, Comp. Anat., p. 378 et seq. 
 
 30 Strasburger, op. cit., p 234. 
 
 31 Bot. Zeitung, 1871, No. i, 2. 
 
 32 Op. cit., p. 359. 
 
 33 Ann. Sci. Nat., Ser. V, xvi (1872), p. 189. 
 
1 68 SCOTCH PINE. 
 
 stage is much reduced, although still green and able 
 to maintain itself for a limited time, while the asexual 
 stage is the conspicuous part of the plant, in fact the 
 only part usually noticed, except by students and fern 
 propagators. 
 
 From the fern to the pine is too great a step to be 
 well understood without considering some intermediate 
 type. Some species of Selaginella would answer this 
 purpose admirably, and it is to be regretted that no 
 species is sufficiently common in this country, either 
 wild or cultivated, to permit the introduction of direc- 
 tions for its study in this manual. It must therefore 
 suffice.to mention one feature of Selaginella indispens- 
 able for a clear understanding of the subject in hand. 
 
 Selaginella, instead of having only one sort of spores, 
 as in the ferns and liverworts, has two, one small (micro- 
 spores), the other large (macrospores). When these 
 spores vegetate, the prothallium from the smaller one 
 bears the male organs (antheridia), and that from the 
 larger the female organs (archegonia). A very marked 
 feature is that the prothallia are greatly reduced, so 
 much so in fact that they never leave the spore or 
 become green, and the one from the smaller spore is 
 even reduced to a single small cell. 34 
 
 To return to pine, we shall find that the reduction of 
 the sexual stage or prothallium is carried a step, and 
 quite a long step further than in Selaginella, while the 
 asexual stage is augmented in the same proportion. 
 The latter in fact is the pine tree the whole plant one 
 would naturally say. It must be borne in mind that in 
 
 34 For further description see Bessey, Botany, p. 385 ; Sachs, Text- 
 book, p. 468. 
 
PLVUS SYLVESTRIS. 169 
 
 the fern the asexual plant produces spores, and that in 
 Selaginella, a more advanced type, it does also, but of 
 two sorts. Does the pine likewise produce spores ? 
 Certainly, although we have so long called them pollen, 
 that we are inclined to forget their true relation, 
 which would be better indicated by the term pollen 
 spores, used by DeBary. 35 These pollen spores cor- 
 respond to the microspores of Selaginella, and like 
 them have the prothallium reduced to one or a few 
 cells, but unlike them do not produce antherozoids. 
 This, however, is a matter of adaptation. Wherever 
 there is water to transport the fertilizing element 
 from the male to the female organs, it is usually 
 an active body (antherozoid), as in Adiantum, Atri- 
 chum and Marchantia, with an exception in Spirogyra, 
 while if it must be transported through the air or the inte- 
 rior of plant tissues a tube leads from the antheridium 
 to the archegonium as in Microsphaera and Cystopus. 
 Pine like other flowering plants has the spores carried 
 bodily through the air in order to bring them into 
 proximity to the female element, then a tube (pollen 
 tube) develops, which connects the male and female 
 organs. Turning now to the female part, which cor- 
 responds to the macrospore of Selaginella, it (now called 
 the embryo-sac) is found so greatly reduced that it 
 never leaves the place in the mother plant where 
 formed. The prothallium is represented by the pri- 
 mary endosperm. The archegonia themselves are 
 much simplified as might be expected. They arise 
 from superficial cells of the endosperm (prothallium). 
 
 35 Morph. u. Biolog. d. Pilze, Mycet. u. Bacterien, 1884, p. 140. 
 
170 SCOTCH PINE. 
 
 Within each is a large nucleated germ cell or oosphere, 
 the part to be fertilized. 
 
 The process of fertilization is as follows : The 
 pollen grains having been lodged in the micropyle 
 upon the apex of the nucellus, the extine is burst and 
 slipped off by the swelling of the intine and its con- 
 tents. By a local growth the intine extends into a 
 tube into which the contents of the larger cell pass by 
 a streaming movement, the smaller cell remaining 
 inert. This pollen tube pushes its way slowly between 
 the cells of the nucellus until it reaches the germ cell 
 in the embryo-sac. Shortly afterward a nucleus almost 
 as large as that of the germ cell appears below the end 
 of the pollen tube. It is to be supposed that it has 
 passed through the wall of the tube, and it is to be 
 regarded as homologous with the body of an an- 
 therozoid. The two nuclei fuse into one, which passes 
 to the end of the germ cell opposite the neck where it 
 gives rise to several four-celled layers, one above 
 another, the lower four of which form the beginning 
 of the embryo. 36 This process of fertilization requires 
 in Pinus sylvestris a little more than a year between 
 the beginning of the growth of the pollen tube and 
 the consummation. 
 
 The fertilized germ cell grows at once into the young 
 plantlet (embryo), as in the fern, but at this stage, 
 unlike the fern, it stops for awhile, and in the passive, 
 well protected condition of a seed may pass a long 
 period before it resumes its growth. This, again, is a 
 special adaptation. All the plants heretofore con- 
 sidered are fully equipped for the dispersion of each 
 
 36 Cf. Strasburger, op. cit, p. 481 et seq. 
 
PINUS S YL VES TRIS. 1 7 1 
 
 succeeding generation through their sexual or asexual 
 spores, or the division of the vegetative members. In 
 the pine the young plantlet is developed before leaving 
 the parent, and were it to continue to grow would 
 either live wholly upon the parent, or be brought into 
 such close competition with it, that the species would 
 speedily become extinct. Therefore, to provide for 
 the proper dispersion of the offspring, the young 
 plantlet is suitably protected, and provided with food 
 for its first growth when again resuming its develop- 
 ment, separated from the parent, and wafted away by 
 the wind in the utmost security. 
 
 This is one of the most characteristic features of the 
 higher plants, from which they might better have been 
 named seed-bearing plants, than flowering plants. 
 
 It is also worthy of notice that the primary endo- 
 sperm which is formed during the first year of the 
 fruit, and on which the archegonia arise, is subsequently 
 destroyed by the deliquescence of the cell-walls ; and 
 from the protoplasm thus set free there is produced 
 in the spring of the second year what may be called 
 secondary endosperm which, with the growing embryo, 
 fills up the embryo-sac and displaces the most of the 
 tissue of the nucellus. 87 
 
 37 Cf. Sachs, Text-book, 2nd Eng. ed. p. 521. 
 
FIELD OATS. 
 
 A vena sativa L. 
 
 PRELIMINARY. 
 
 THE cultivated grass known as oats is too familiar to 
 need description. Specimens should be collected at 
 the time when some flowers of the panicle are 
 expanded and others are yet in the bud. This plant 
 begins to bloom shortly after the panicle is liberated 
 from the sheath. The time of blossoming is so little 
 marked by external changes that there is great danger 
 that specimens will be collected too late. Care should 
 be taken in lifting the plants from the ground not to 
 detach the empty grain from which it grew, which will 
 almost certainly be done if the plants are pulled up. 
 They should be dug and the dirt shaken gently from 
 the roots, which may be further cleaned by washing. 
 
 The requisites for the complete study of the plant 
 are entire plants, preserved in alcohol ; a handful of 
 threshed oats ; alcohol ; magenta ; potassic hydrate ; 
 and iodine. 
 
 LABORATORY WORK. 
 GROSS ANATOMY. 
 
 A. GENERAL CHARACTERS. Note the four parts 
 of the plant : 
 
A VENA SATIVA. 173 
 
 1. The roots. 
 
 2. The upright main axis, the stem, with numerous 
 branches near the top. 
 
 3. The lateral appendages of the stem, the leaves. 
 
 4. The surface appendages on the roots and leaves, the 
 trichomes, in both instances extremely minute. 
 
 B. THE ROOTS. In a plant which has the emptied 
 grain from which it grew still attached, note 
 
 1. The small group of roots arising from one end of the 
 grain, the strongest of which is fat primary root. 
 
 2. The stem emerging from the other end, the first inter - 
 node of the stem. 
 
 3. At a certain point, 1 the second node of the stem, a whorl 
 of secondary roots. 
 
 4. At one or two succeeding nodes, a like whorl of sec- 
 ondary roots. 
 
 5. Make a diagram, showing the position of the roots 
 and their relation to the lower part of the stem. 
 
 Cut a transverse section of one of the large secondary 
 roots. Examine by transmitted light. Note 
 
 6. The round central spot of firmer tissue, \.\\z fibro-vas- 
 en Jar bundle. The openings in it are the larger vessels. 
 
 7. The loose, pith-like cortical portion. 
 
 8. The root-hairs, attached to the edge. 
 
 9. Draw. 
 
 1 Known to agriculturists as the " tillering point." The length of 
 this first internode depends to a considerable extent on the depth of plant- 
 ing the seed. 
 
174 FIELD OATS. 
 
 Strip off the cortical portion of one of the large secondary 
 roots. Notice 
 
 10. The slender, strong fibre-vascular axis which remains. 
 
 Examine some plants three or four days old, which have 
 been grown on the surface of wet blotting paper. Note 
 
 11. The position of roots and stem with respect to the 
 grain. 
 
 12. The abundant root-hairs. Notice their relative length 
 on different parts of the root, and where absent. 
 
 13. The opaque tip of the root covered by the conical root- 
 cap. 
 
 C. THE STEM. Notice that it is completely encased by 
 the sheathing bases of the leaves. Uncover a portion of 
 the stem by removing one of the leaves and its sheath, and 
 note 
 
 1. Its shape, and polished surface. 
 
 2. Its nodes and internodes. Bisect the stem longitudinally 
 through a node and a portion of an internode. Note 
 
 a. The solid node forming a partition between the 
 cavities of the internodes. 
 
 b. Draw. 
 
 Look through the split stem at a bright light, and note 
 
 3. The numerous threads, traversing the stem lengthwise, 
 the fibro-vascular bundles. 
 
 Cut a transverse section and examine by transmitted light, 
 and note 
 
 4. A very firm, more opaque external layer, the cortical 
 layer. Notice its variable thickness. 
 
 5. In the cortical layer, pairs of darker spots. These are 
 clusters of chlorophyll-bearing cells. 
 
ATENA SATITA. 175 
 
 6. The remainder of the section made up of large rounded 
 cells, parenchyma, scattered through which are 
 
 7. Masses of firmer tissue, the fibro-vascular bundles, each 
 having three or four openings, the vessels. 
 
 8. Draw the section. 
 
 Cut a number of longitudinal sections ; in them make 
 out 
 
 9. The denser cortical portion. 
 
 10. The more transparent parenchyma. 
 
 11. The fibro-vascular bundles. 
 
 12. In a section not passing through a fibro-vascular bun- 
 dle, the strip of darker chlorophyll-bearing tissue 
 under a very narrow cortical layer. 
 
 13. Draw a section, showing as much as possible of the 
 structure. 
 
 D. THE LEAF. Note 
 
 1. Its sheathing base. Observe the extent of stem cov- 
 ered by each sheath. 
 
 2. The split in the sheath ; its position and extent. 
 
 3. On the upper surface at the point where the sheath 
 ceases, a thin membranous outgrowth, the ligule. 
 Notice its shape and apex. Draw. 
 
 4. The place of attachment of the leaves. 
 
 5. The remainder of the leaf, the blade. Note 
 
 a. Its shape. 
 
 b. The numerous veins ; their direction and relation 
 to the ridges. 
 
 c. The green tissue (bleached by alcohol) between 
 the veins, the mesophyll. 
 
I7 6 FIELD OATS. 
 
 Cut a transverse section of the blade, and note 
 
 6. The variable thickness of the leaf. 
 
 7. The sections of the fibre-vascular bundles. 
 
 8. On the upper edge, large cells between the ridges, the 
 hygroscopic cells, which cause the leaf to roll when dry. 
 
 E. THE FLOWERS. 
 
 i. The arrangement of the flowers, anthotaxy. Note 
 
 a. The central stem of the flower cluster, the main 
 axis of inflorescence. 
 
 b. Its lateral branches, secondary axes. Notice their 
 relative lengths. 
 
 c. That some of the secondary axes are branched, 
 others not, thus constituting a panicle. 
 
 d. Make a diagram of the mode of branching. 
 
 e. That each ultimate branch bears not a single 
 flower, but a cluster of three (sometimes two) 
 flowers, a spikelet, at the thickened extiemity. 
 The entire inflorescence is thus compound, a 
 panicle of spikelets. 
 
 Detach a spikelet, and note 
 
 /. Two bracts at the base of the spikelet, completely 
 inclosing the flowers, the empty glumes. Notice the 
 position of these glumes with respect to each 
 other and their points of attachment. Detach 
 them, and note 
 i. Their shape. 
 
 ii. The parallel veins, nerves ; the number in 
 each glume, the termination above, the deli- 
 cate cross (anastomosing) veinlets. 
 iii. Draw. 
 
A VEX A S A 'I IV A. 177 
 
 g. The three flowers inclosed by the empty glumes ; 
 
 their relative size 2 and position on 
 //. The flattened axis on which they are borne, the 
 
 rhachis of the spikelet. 
 /'. The tufts of minute hairs at the base of the lowest 
 
 flower. 
 j. Draw a spikelet, showing the empty glumes and 
 
 flowers separated from one another. 
 
 2. The structure of the flowers. Detach the lowest flower 
 in the spikelet. Note 
 
 a. The bract, flowering glume, 3 which almost incloses 
 the flower. It sometimes bears a long bristle-like 
 appendage or awn on its outer surface ; note 
 position when present. Detach this bract entire, 
 and note the size, shape, surface, texture, notched 
 apex and number of nerves. Draw. 
 
 From another flower cautiously detach the flowering 
 glume by cutting and tearing it away piece by piece, leav- 
 ing only a bit of its base, being careful not to injure 
 
 b. r Y\\& flower proper. Observe 
 
 i. A large bract-like body, the palet, 4 its infolded 
 margins, shape, nerves, and the presence and 
 position of the trichomes on its outer surface ; 
 contrast it with the flowering glume. Draw ; 
 also make a diagram of a transverse section 
 at its middle. 
 
 ii. Two small bract-like bodies, the lodicules, 
 situated between the edges of the palet. Ob- 
 serve their shape and texture. Draw. 
 
 7 The third is rudimentary and lies close to the inner side of the upper 
 flower. 
 
 8 Called the lower palet in most systematic works. 
 4 Called the upper palet in most systematic works, 
 
178 FIELD OATS. 
 
 iii. The three similar sta mem. Examine one care- 
 fully, and note three parts : 
 
 a. The slender thread, filament, carrying at 
 its apex 
 
 /?. A two-lobed body, the anther ; note 
 the deep groove lengthwise of each lobe, 
 and the point of attachment of the fila- 
 ment. 
 
 y. Tear open an anther, or examine one 
 which has burst, and notice the cavities 
 contain ing pollen ; the color and powderi- 
 ness of the grains. 
 
 d. Draw a stamen, 
 iv. The hairy body in the midst of the stamens, 
 
 the pistil. Note its three parts: 
 
 a. The large, top-shaped part at the base, 
 clothed with white hairs, the ovary. 
 
 /?. The two thread-like bodies arising from 
 the top of the ovary, the styles. 
 
 y. The numerous branches 5 of the styles 
 arranged like the barbs of a feather, the 
 stigmas. 
 
 d. Draw a pistil. 
 
 Cut a pistil in two longitudinally between the styles, 
 and notice 
 
 . The thick but delicate wall of the ovary. 
 
 2,. The ovule of denser tissue closely adher- 
 ing to it, and mostly occupied by 
 
 77. A cavity, filled when growing with the 
 transparent endosperm, which cannot now 
 be easily detected. In this cavity notice 
 
 5 If hidden by many adherent pollen grains, brush them off with a camel's- 
 hair brush. 
 
A VENA SATIVA. 179 
 
 0. The early stage of the young plantlet of 
 the seed, the embryo. 
 
 1. Illustrate with diagram. 
 
 Compare with this flower the second and third flowers of 
 the spikelet. Note, in the latter, the absence of the inner 
 organs, leaving only the flowering glume, palet, and some- 
 times the stamens. 
 
 F. THE FRUIT. Study ripe oats which have been 
 threshed or shelled out in the hand. Strip off the chaff 
 (flowering glume and palet) which incloses the fruit. Note 
 
 1. The white hairs which cover it, especially at the upper 
 end. 
 
 2. The longitudinal groove ; its position as to the palet. 
 
 3. The scar at the base of the grain opposite the groove, 
 marking the position of the plantlet within. 
 
 Cut across the middle of a grain, and note 
 
 4. The depth of the groove, and the uniform floury 
 contents ; test with iodine. 
 
 5. That the wall of the ovary and the coats of the ovule 
 have become so closely united and thin as to be indis- 
 tinguishable, thus constituting the fruit a caryopsis or 
 
 grain. 
 
 6. Draw the section. 
 
 From a soaked grain carefully remove the " skin " (the 
 wall of the ovary together with the seed coats) on the side 
 opposite the groove, from the lower end to the middle. 
 There will then be seen a face view of 
 
 7. The embryo. Note 
 
 a. The large elongated-triangular body forming the 
 
I So FIELD OA TS. 
 
 upper part of the embryo, the cotyledon or scutellum. 
 
 b. The pointed lower extremity, the root sheath. 
 
 c. Near (below) the center of this face of the embryo, 
 a minute bud, \he plumule. 
 
 d. Just below the base of the plumule, a very short 
 stem, the caulicle? 
 
 e. Draw the embryo as it lies exposed. 
 
 Bisect a grain longitudinally through the groove. Mount 
 also a thin section from the cut surface. Note 
 
 f. The scutellum, with its back against the starchy 
 part of the seed, its face just under the "skin" 
 at the upper part of the embryo. 
 
 g. The plumule, on the face of the scutellum, at the 
 upper end of 
 
 h. The caulicle; easily recognized as the whitish 
 part where the scutellum and plumule merge. 
 At its lower extremity is 
 
 /. The root, a small rounded point, over which is 
 /. The root-sheath, which forms the lower extremity 
 
 of the embryo. 
 k. Draw the section. 
 
 Take a series of transverse sections from the bottom of 
 the grain upward. Examine the successive cut surfaces and, 
 comparing with the longitudinal sectin, determine the 
 various parts seen, root-sheath, root, caulicle, plumule, 
 scutellum. Draw those which show the section of root and 
 root-sheath, and the section of plumule and scutellum. 
 
 MINUTE ANATOMY. 
 
 A. THE ROOTS. Cut a transverse section of one of the 
 lateral roots at a little distance from the stem. Examine 
 with a low power, and note the two regions : 
 
 6 111 defined and difficult to see. 
 
A TEN A SATIVA. 181 
 
 1. The cortical, thin-walled cells. 
 
 2. The fibro-vascular, thick-walled cells. 
 Examine with a high power, and note 
 
 3. The thin-walled epidermis. Observe its irregularity, 
 and the mode of attachment of the root-hairs. Draw. 
 
 4. The cortical parenchyma, with sclerenchyma either 
 intermixed, or in older roots forming an outside layer. 
 Draw. 
 
 5. The bundle sheath ; the relative thickness of outer and 
 inner walls ; the pits. Draw. 
 
 6. The fibro-rasciilar bundle. Study 
 
 a. The smaller thick-walled cells constituting most 
 of the bundle. 
 
 b. The vascular tissue ; four to six (sometimes more) 
 \ax%t pitted vessels symmetrically disposed. Between 
 each of these and the bundle sheath (also some- 
 times near the center) a dozen (more or less) of 
 smaller pitted vessels. 
 
 c. Numerous channel-pits in all the thick-walled 
 cells. 
 
 d. Draw a portion of the bundle. 
 
 Cut a longitudinal section of the same root. Examine 
 with a high power, and note 
 
 7. The epidermal cells. Observe the bases of root-hairs, 
 and their relations to the epidermal cells. Draw. 
 
 8. Elongated cortical parenchyma and occasionally 
 sclerenchyma. Notice the pits. Draw. 
 
 9. The bundle, sheath ; cells elongated, rather difficult to 
 distinguish. Draw. 
 
 10. The fibro-vascular bundle. Study 
 
182 FIELD OATS. 
 
 a. The pitted fibrous cells, tracheides y which constitute 
 most of the bundle. 
 
 b. The one or two pitted vessels. 
 
 c. Draw, showing both vessels and tracheides. 
 Mount about one centimeter of the tip of a root from 
 
 plants that have been grown upon blotting paper. Exam- 
 ine with a low power, and note 
 
 11. The root-hairs. Observe their relative length. 
 
 12. The root-cap ; the outer cells sloughing off. Draw. 
 Study the root-hairs with a high power. Notice 
 
 13. The shape, mode of attachment and contents. Draw. 
 Cut a median longitudinal section of the tip of a root, 
 
 including the root-cap. 7 Treat with potash, examine with 
 a high power, and note 
 
 14. The blunt, or even notched tip of the root proper. 
 
 15. The sharp conical root-cap. Note the shape of the 
 cells near the root-tip, and the changed shape near the 
 periphery. 
 
 1 6. The growing point, a cluster of small cells, just back of 
 the root-cap, in the middle of the root-tip. 
 
 17. A short distance behind the tip of the root, the slight 
 differentiation of the tissues into three regions : 
 
 a. A central one, the plerome. 
 
 /;. An outer one, consisting of a single row of cells, 
 
 the dermatogen. 
 
 Between the plerome and dermatogen, the periblem. 
 
 Trace these three regions down to the growing 
 
 point, and notice their relations there. 
 
 7 This is very difficult to do if fresh roots are used, but easier by using 
 roots that have been kept for a few hours in alcohol. The student should 
 cut a series of sections through the whole root. The median one can then 
 be selected. 
 
A VEX A SATir.l. 183 
 
 e. Trace them backward ; notice that the plerome 
 becomes the fibro-vascular bundle ; the periblem, 
 the cortical parenchyma ; the dermatogen, the 
 epidermis. 
 
 Cut a transverse section of the oldest part of a root which 
 has grown on blotting paper. Examine with a high power. 
 Compare with the section of the large lateral roots, already 
 studied. Notice 
 
 1 8. The origin of the root-hairs. 
 
 19. The differences in the fibro-vascular bundle, particularly 
 the presence of a large axial vessel. 
 
 r>. THE STEM. Cut a transverse section from one of the 
 younger parts of the stem, e. -., between the flower cluster 
 and the first leaf. Examine with a low power, and note 
 
 1. An outer cortical part, of varying thickness, composed 
 of small dense-looking cells, the epidermis and hypo- 
 derma. 
 
 2. In the cortex lighter spots, in pairs, at almost regular 
 i ntervals, chloropJn 'll-bcaring parenchyma. 
 
 3. An inner part, consisting of large empty parenchyma 
 cells, the fundamental parenchyma, with fibro-vascular 
 bundles at regular intervals. 
 
 Examine with a high power. Study 
 
 4. The epidermis. Note the thick walls, showing two 
 layers, and the cuticle. Draw. 
 
 a. Observe in some sections a pair of smaller, peculiar 
 cells in the epidermis over an intercellular space 
 in the chlorophyll-bearing parenchyma, the guard 
 cells of a stoma. The two adjacent epidermal cells 
 are also modified somewhat. Draw. 
 
 5. The hypoderma. Note the thick walls of the cells 
 
184 FIELD OATS. 
 
 which increase in size toward the parenchyma, but do 
 not merge into it. Draw. 
 
 6. The chlorofhyll-bearing parenchyma. Note 
 
 a. The shape, size and arrangement of the cells. 
 
 b. The thin walls. 
 
 c. The contents ; protoplasm and chlorophyll bodies 
 which are green, if fresh stems are used. Notice 
 the position of the chlorophyll bodies. 8 
 
 d. Draw a few cells. 
 
 7. The fundamental parenchyma. Note the size and shape 
 of the cells, and the triangular intercellular spaces. 
 Draw a few cells. 
 
 8. The fibro-vascular bundles. Notice the two series of 
 bundles : the larger ones nearer the central cavity of 
 the stem ; the smaller between the paired groups of 
 chlorophyll-bearing parenchyma. In the larger ob- 
 serve 
 
 a. The external sheath, an irregular layer of cells, 
 with slightly thickened walls, 9 surrounding the 
 bundle, and thicker on its peripheral side. Exam- 
 ine it in a section from an older part of the stem ; 
 note the thickness of the walls. 
 
 b. The tracheary tissue; on the right and left of the 
 bundle two large pitted vessels ; toward the axial 
 side one or two annular vessels j between the 
 large pitted vessels a transverse band of smaller 
 pitted vessels. 10 
 
 c. Between the annular vessels and the external 
 
 8 They may be made plainer by staining with magenta. 
 
 9 If it can not be discerned, stain slightly with magenta ; these cells 
 take a deeper red than the rest. 
 
 10 Stained a deeper red in the magenta-treated section. 
 
A VENA SATIVA. 185 
 
 sheath sometimes an intercellular cavity formed 
 by breaking in growth. 
 d. Toward the peripheral side of the bundle a group 
 
 of thin- walled conducting cells." 
 c. Draw the bundle. 
 /. Compare the structure of the smaller bundles with 
 
 the foregoing, noting differences. 
 
 Cut a number of longitudinal sections of the stem, and 
 examine with a high power. Study 
 
 9. The epidermis. Note 
 
 a. The thickened outer wall ; elongated shape; chan- 
 nel pits. 
 
 b. The alternately long and short cells in some 
 sections. 
 
 c. Draw. 
 
 Some of the sections will be likely to pass through a 
 stoma. Examine 
 
 d. The guard cells ; note the enlarged ends and nar- 
 row body. Draw. 
 
 10. The hypoderma ; note the extreme elongation and 
 tapering ends of the cells. Draw. 
 
 11. The chlorophyll-bearing cells ; note their shape, arrange- 
 ment and contents. Draw. 
 
 12. The futidamental parenchyma; note the size and 
 shape of the cells, and the thin places in the walls. 
 Draw a few cells. 
 
 13. The fibro-vasciilar bundles ; note in the various sec- 
 tions ia 
 
 a. The slightly thickened, sparsely pitted, elongated 
 
 11 Unstained with magenta. 
 
 '-' No one section can be found to show all points. 
 
1 86 FIELD OATS. 
 
 cells of the external sheath having slightly oblique 
 end walls. 
 
 b. The delicate walls and elongation of the conduct- 
 ing cells. 
 
 c. The pitted vessels, large and small. 
 
 d. The annular vessels. Notice the various positions 
 of the rings. Study their cut ends where the 
 razor has passed along a vessel. 
 
 e. Draw a few cells of each tissue. 
 
 Cut a thin slice from the surface of a stem, examine 
 with a high power, and note 
 
 14. The epidermis. 
 
 a. The cells above the hypoderma ; shape and ar- 
 rangement. 
 
 b. The cells above the chlorophyll tissue, including 
 the stoma ; shape and arrangement. 
 
 c. The numerous pits in the surface wall, and in the 
 side walls beneath. 
 
 d. Draw. 
 
 C. THE LEAF. Cut a transverse section, and examine 
 with a high power. Study 
 
 i. The epidermis. Notice 
 
 a. Its cuticularized outer wall with minutely uneven 
 free surface. 
 
 b. Ite guard cells. Note 
 
 i. The different appearance of these cells, 
 according as the section has passed through 
 the bodies or ends. 
 
 ii. The small size and thick walls of the body, 
 the larger size and thinner walls of the ends. 
 
 c. The modified epidermal cells adjoining the guard 
 cells. 
 
A VEX A SATIVA. 187 
 
 d. Draw various sections of stomata, with adjoining 
 cells of the epidermis. 
 
 e. The modified large epidermal cells in the depres- 
 sions on the upper surface, the hygroscopic cells. 
 Draw. 
 
 /. The modified epidermal cells at the summit of each 
 ridge; sometimes teeth may be seen. Draw. 
 
 2. The hypoderma. Note its position and the character 
 of the cells. 
 
 3. The mesophyll, all the chlorophyll-bearing part of the 
 leaf. Note 
 
 a. The slight elongation of those cells next the epi- 
 dermis, forming palisade parenchyma. 
 
 b. The large intercellular space under each stoma, and 
 the numerous smaller ones in other places. 
 
 c. The abundant chlorophyll bodies. 
 
 4. The fundamental tissue ; often reduced to only one 
 row of large empty cells surrounding the bundles. 
 
 5. ^\^ fibro-vascular bundles ; compare those forming the 
 midrib and main veins of the leaf with those studied in 
 the stem. Compare with these the bundles of the 
 smaller veins, noting what tissues are absent from 
 them. 
 
 6. Draw a portion of the section, including a large fibro- 
 vascular bundle, and some cells of the mesophyll and 
 fundamental tissue. 
 
 7. Make a diagram of the leaf section to show relative 
 position and size of the different parts. 
 
 Strip off two pieces of the epidermis. Mount one piece 
 with the outer surface uppermost, and the other with the 
 inner surface uppermost. Note 
 
1 88 FIELD OATS. 
 
 8. The epidermal cells. 
 
 a. The shape of those lying above a vein, together 
 with the short strong trichomes, each bearing a 
 very sharp point, directed forward. 
 
 b. The shape of those lying among the stomata. 
 
 c. The stomata. Note 
 
 i. The regular arrangement in double or triple 
 
 rows, 
 ii. The pair of narrow epidermal cells, which 
 
 stand one on each side of the guard cells, 
 iii. The shape of the guard cells ; the thick walls 
 
 of the body and thin walls of the ends, 
 iv. Draw, showing the several sorts of epidermal 
 
 cells. 
 
 9. The shape and contents of the mesophyll cells, some of 
 which will almost invariably adhere to the epidermis 
 when stripped off. Draw. 
 
 10. Make a transverse section of the leaf sheath, and note 
 its intermediate character between that of the stem and 
 of the leaf blade already studied. Draw sufficient to 
 show the various tissues, and their arrangement. 
 
 D. THE FLOWER. 
 
 i. The glumes and palets. Make a transverse section 
 through the upper part of a spikelet and transfer it to 
 the slide without disarranging the parts. Note 
 
 a. The thin-walled cells forming the inner portion, 
 and the thick-walled cells forming the outer por- 
 tion of each part. Draw from two or more 
 regions. 
 
 b. The angles of the palets, bearing stiff trichomes. 
 Draw. 
 
A VENA SATIVA. 189 
 
 2. The anthers. Tear off bits of the wall of an empty 
 anther. Mount one outside up and the other inside up. 
 Focus on the surface of the first, and note 
 
 a. The epidermis ; its wrinkled walls ; the shape of 
 its cells. Draw. 
 
 Focus on the surface of the second, and note 
 
 b. The emfotJicciuM, the layer of cells lining the 
 anther. Observe 
 
 i. The infolded thickenings of the side walls of 
 
 the cells. 
 
 ii. The shape of the cells, 
 iii. Draw. 
 
 Cut a transverse section through the lower part of a 
 spikelet which has not bloomed, and transverse sections of 
 the anthers will be obtained. Notice 
 
 c. The large inflated epidermal cells. 
 
 d. The very narrow endothecial cells, with the thick- 
 enings of the walls extending the full height, mak- 
 ing it difficult to distinguish their outline. 
 
 e. Draw a few of the two kinds of cells. 
 Under low power, notice 
 
 /. The two lobes of the anther, theca. 
 
 g. The connective which joins them, containing a fibro- 
 
 vascular bundle. 
 //. The four cavities, appearing like two after dehis- 
 
 cence. Usually the manner of dehiscence can 
 
 be detected. 
 
 Using the same section, under high power, notice 
 
 3. The pollen. 
 
 a. The shape of the cells. 
 
 b. The small globular protuberance sometimes seen 
 when the spore lies properly. 
 
1 90 FIELD OATS. 
 
 c. The optical section of the wall ; its continuity inter- 
 rupted at the protuberance. 
 
 d. The contents. Burst some spores by pressing 
 lightly on the cover-glass with a needle. Note 
 
 i. Here and there entirely empty bursted sacs, 
 the extine. Notice the minute roughening 
 of the surface ; the thin spot or opening, 
 through which in some cases when unburst the 
 intine protrudes. 
 
 ii. The contents of some spores surrounded by the 
 intine t escaped from the extine and become 
 much larger. In some cases the protuberance 
 may still be seen. 
 
 iii. The contents of other spores free in the water 
 of the slide, showing innumerable fine gran- 
 ules. Note their shape, and treat with iodine 
 to determine their nature. 
 
 e. Draw an uninjured spore, showing its structure. 
 
 4. The styles and stigmas. Cut off one of the styles near 
 its attachment. Mount and examine with a low 
 power. Note 
 
 a. The tapering style with 
 
 b. Numerous undivided branches, the stigmas, 
 roughened with innumerable points. 
 
 c. The grains adhering to the stigmas. 
 Examine with a high power. Observe 
 
 d. The thin-walled nucleated cells, forming the stig- 
 mas ; the proximal ends are overlapped by other 
 cells. 
 
 e. The adherent grains. Notice that some of the 
 spores have emitted through the perforation in 
 the extine a slender tube which penetrates the 
 stigma. Notice that the granules of the pollen 
 
A VENA SATIVA. 191 
 
 spore also enter this tube. Observe that some 
 spores have become empty. 
 
 f. Draw, showing structure of stigmas and the 
 entrance of a pollen tube. 
 
 5. The trichomes of the wary. Cut off, mount, and 
 examine with a high power some of the trichomes which 
 clothe the apical portion of the ovary. Note shape and 
 contents. Draw. 
 
 E. THE FRUIT. Remove the chaff from a grain, and 
 cut a transvense section near the middle, having previously 
 soaked it in warm (not hot) water for a few minutes. 13 
 Note 
 
 1. While mounting, the abundant whitish powder which 
 escapes into the water, clouding it more or less. 
 
 Examine with a high power and note 
 
 2. The outermost coat of the fruit, the ovary wall, some- 
 times splitting into two layers ; the cells can only be 
 made out with great difficulty. 
 
 3. The layer of large cells, containing granular proteid 
 matters, chiefly gluten. Note shape, and test contents 
 with iodine. Draw. 
 
 4. The large cells packed with granules of starch, made 
 blue by the iodine. The outline of these cells is best 
 seen when the starch has escaped from them. 
 
 5. The tip of the embryo will usually appear at one side of 
 the section. 
 
 Cut a median longitudinal section through the groove of 
 a soaked fruit. Treat with potash to clear up the embryo, 
 and examine with a low power. Note 
 
 13 An immersion of an hour or longer in cold water will answer the 
 same purpose. 
 
*9 2 FIELD OATS. 
 
 6. The three parts of the fruit : the walls of the ovary 
 and gluten-containing cells ; the starchy part of the 
 grain ; the embryo. 
 
 Study the embryo / note 
 
 7. The long leaf, scutellum, next the starch. 
 
 8. The bud, plumule, near the base of the scutellum, 
 showing one or two leaves. 
 
 9. The root near the base of the embryo, with its root-cap, 
 and enveloped by 
 
 10. The root-sheath ; notice that it is continuous with 
 
 11. The short stem, caulicle, to which the scutellum is 
 attached, bearing the plumule at its upper and the root 
 at its lower end. 
 
 Examine with high power. Note 
 
 12. The tissues of the fruit, essentially as in the trans- 
 verse section. 
 
 13. The tissue of the embryo ; parenchyma with much 
 protoplasm. 
 
 ANNOTATIONS. 
 
 The division of the slender, slowly tapering stem of 
 Avena into ring-like nodes and elongated internodes 
 shows these features distinctly marked for the first 
 time. The disposition of the material in the form of 
 a hollow cylinder gives greater rigidity than would 
 the same amount of material in a solid stem. 
 
 At some of the lower nodes of the stem the endog- 
 enous formation 14 of roots can be well seen, as young 
 
 14 Cf. Prantl and Vines, Text-book, p. 22. 
 
AVENA SATJVA. 193 
 
 roots can be frequently found just breaking through 
 the superficial tissues. 
 
 The leaves of oats are sharply distinguished into a 
 sheathing base and a spreading blade. The membra- 
 nous outgrowth, the ligule," which is found at their 
 junction, is common in leaves of this character. 
 
 The flower of oats, like that of the pine, is a meta- 
 morphosed shoot, in which the axis is the stem, and 
 the lateral organs which it bears, leaves. At the base 
 of each spikelet are to be found two glumes or bracts, 
 which thus subtend and more or less completely inclose 
 the whole cluster. At the base of each flower is a 
 single bract, the flowering glume, having the flower in 
 its axil. Concerning the homology of the palet and 
 lodicules much discussion has arisen. Payer 1<s asserts 
 that the palet is a double organ and that the two keels 
 on the palet are primitively distinct. Schacht 17 sees 
 in the palet two parts of a trimerous whorl, of which 
 the anterior part is suppressed. Roper, Wigand, 
 Nageli and others conclude from comparative and 
 developmental researches that the palet is primitively 
 single and takes on its two-keeled condition subse- 
 quently. 18 Hackel 19 believes " that the palea and the 
 pair of lodicules (when two only) are each single, more 
 or less bifid organs, and that they and the third lodi- 
 cule, when present, must be regarded as two or three 
 
 15 For a statement of its homology see Gray, Struct. Botany, pp. 106, 
 211. 
 
 16 Organogenic de la fleur, p. 701. 
 11 Das Mikroskop, 2 Aufl., p. 170. 
 
 18 Cf. Eichler, Bluthendiagramme, p. 120. 
 
 19 Untersuchungen liber die Lodiculae der Graser, Engler's Bot. Jahr- 
 biicher, i, p. 336. 
 
194 FIELD OATS. 
 
 bracteoles inserted fore and aft on the floral axis below 
 the flower, and he has made out a good case in favor 
 of his view but perhaps not an unanswerable one." 20 
 Bentham " adds : " The search for homologies to the 
 palea and lodicules in the orders nearly allied to the 
 Graminece has met with but little success ; " and again, 
 " The palea and lodicules of Graminece may represent 
 perianth segments of an outer and inner series, though 
 I by no means pretend to assert it as a proved fact." 
 Again," " In all cases, the palea, whatever its origin, 
 is called upon in conjunction with the subtending 
 glume to perform more or less of the functions of the 
 deficient or absent perianth." 
 
 It is to be noticed that the male and female repro- 
 ductive organs occur in the same flower, which is 
 therefore hermaphrodite. The stamens of oats are 
 to be looked upon as metamorphosed leaves, as in the 
 pine ; it seems probable, though not definitely proved, 
 that the pollen sacs are homologous with those of the 
 pine. The immature pollen spore is two-celled, as in 
 most other angiosperms, 23 and it is doubtful whether 
 there is any trace of a prothallium. This stage in the 
 life cycle of the plant, which is so marked in the moss 
 and liverwort, far less prominent in the fern, reduced, 
 if it can be considered present at all, to but a cell or 
 two in the pine, is in this plant probably entirely sup- 
 pressed. 
 
 Attention is called to the fact that the ovule is not 
 
 20 Bentham, Notes on Gramineae, Jour. Linn. Soc., xix, p. 23. 
 
 21 L. c., p. 24. 
 
 ' 2 L. C.,p. 2 5 . 
 
 23 Cf. Strasburger, Neue Untersuchungen, p. 5, 
 
A VENA SATIVA. 1 95 
 
 naked as in pine, but that it is surrounded by an organ 
 peculiar to angiosperms, the ovary, which in this plant 
 adheres to the surface of the ovule. It is much better 
 developed in Trillium and Capsella, to which for its 
 study the student is referred. Since the ovule is thus 
 inclosed, stigmas have been developed as naked pollen- 
 catching surfaces, to which the pollen spores can 
 adhere, and through whose loose tissues they can eas- 
 ily send their tubes. 
 
 The adherence of the ovary wall to the ripened seed 
 gives rise to a fruit peculiar to grasses, the grain, which 
 is commonly mistaken for a simple seed. 
 
 The fibre-vascular system is well developed in oats, 
 and is of the typical monocotyledonous form. The 
 hypodermal fibers of both stem and leaves give addi- 
 tional strength to these organs. The bundles through- 
 out the stem are of the collateral type, as in the pine, 
 but with this difference ; whereas in the pine there 
 remains a cambium layer between the xylem and 
 phloem, here there is no cambium. The continued 
 growth of the bundle is therefore impossible, whence 
 it is known as a closed bundle. The axial bundle of the 
 root is, like that of the fern, a radial one. In the fern 
 root a single apical cell forms the growing point of 
 the root ; in oats the apical cell is replaced by a clus- 
 ter of cells. The remark respecting the root-epidermis 
 of Adiantum " is equally applicable here concerning the 
 older roots. 
 
 In the leaves the most novel structure is the groups 
 of hygroscopic, or as they were first named by Duval- 
 
 24 Cf. also Goodale, Physiological Botany, p. 108. 
 
196 FIELD OATS. 
 
 Jouve," bulliform cells. They are found in all grasses 
 that roll and unroll their leaves. These cells when 
 they lose part of their moisture contract and roll up 
 the leaf, which again expands upon their regaining it. 
 This movement reduces the amount of surface available 
 for evaporation, and is a safeguard for the plant. It 
 will be remembered that the moss leaf accomplishes 
 the same result, but without a specialized apparatus. 
 
 t5 Etude anatomique de quelques Graminees, 1870, p. 320. 
 
TRILLIUM. 
 
 Trillium rccurvatum Beck. 
 
 PRELIMINARY. 
 
 THE Trillium designated, as well as T. sessile, is 
 found in the spring, generally in rich woods, and may 
 be readily recognized by the naked stems, from fifteen 
 to thirty centimeters (six inches to a foot) or more high, 
 bearing at the summit a circle of three broad netted- 
 veined leaves, at the center of which (the apex of the 
 stem) stands a single sessile dark-purple flower. The 
 stem rises from a deep-seated, somewhat toothed, very 
 thick rootstock, which bears the fibrous roots 
 along its under surface. In the other Trilliums, which 
 are at all common, the flowers are usually white 
 or pinkish, or purple in one case, and stalked. Any 
 species may be used for the laboratory work. 
 
 Although Trillium is now considered a member of 
 the lily family, the largest order of petaloideous mon- 
 ocotyledons, it is not a very characteristic member, 
 but has been selected for its general distribution, its 
 completeness and simplicity, and for its convenient 
 size. 
 
 The materials needed are fresh or alcoholic spec- 
 
198 TRILLIUM. 
 
 imens of roots, rootstocks, stems, leaves, flowers 
 and fruit ; potassic hydrate ; magenta ; and iodine. 
 
 LABORATORY WORK. 
 
 GROSS ANATOMY. 
 
 A. GENERAL CHARACTERS. Note 
 
 1. The main axis, consisting of a thickened, horizontal, 
 under-ground stem, the rootstock, and a single vertical 
 branch, the aerial stem, bearing a terminal flower. 
 
 2. The rootstock, bearing as lateral appendages the roots, 
 and modified leaves in the form of broad membranous 
 scales. 
 
 3. The aerial stem, bearing as lateral appendages a whorl 
 of three leaves, and the parts of the flower. 
 
 B. THE ROOTS. Note 
 
 1. Their arrangement on the rootstock. 
 
 2. The almost entire absence of branching. 
 
 3. The surface, especially the transverse wrinkles on older 
 parts. 
 
 4. The root-hairs. 
 
 Mount a transverse section of the proximal portion of a 
 large root, and notice 
 
 5. The presence and relative areas of three regions: 
 a. The cortical region of two layers : 
 
 i. An outer layer of small cells. 
 ii. An inner layer of large, irregular, loose cells, 
 often torn through in sectioning, the unequal 
 
TRILLIUM RECURVA TUM. 199 
 
 development of which gives rise to the 
 wrinkling. 
 
 b. The median large-celled or parenchyma region. 
 
 c. The central or fibro-vascular region, in which may 
 be detected the large openings of four or five 
 tracheary vessels. 
 
 Mount a longitudinal section through the center of the 
 root and notice 
 
 6. The several regions as before. 
 
 7. The depth of the surface wrinkles. 
 
 8. Diagram both the transverse and longitudinal sections. 
 
 C. THE ROOTSTOCK (Subterranean Stem). Note 
 
 1. The shape and thickness. 
 
 2. The succession of nodes and inter nodes. 
 
 a. The number in an unbroken rootstock. 
 
 b. The scars of former branches, and the varying 
 number of intervening nodes. 
 
 c. The irregular growth of the internodes. 
 
 3. The prevailing number of roots from each node. 
 Mount a transverse section ; notice 
 
 4. 1\& three parts : 
 
 a. The extremely narrow brownish cortical region, 
 forming the boundary of the section. 
 
 b. The great mass of the stem, whitened with the 
 reserve food material. In thin parts of the sec- 
 tion, where the food material has been washed out 
 in mounting, note 
 
 i. The delicate colorless tissue, fundamental par- 
 enchyma. 
 
200 TRILLIUM. 
 
 Tease a bit of the stem in a drop of water on another 
 slide, treat with iodine, and note 
 
 ii. The color imparted to the food material, indi- 
 cating its nature. 
 
 c. Scattered irregularly through the section the 
 comparatively few small dark areas, the fibro- 
 vascular bundles. 
 Make a longitudinal section, and notice 
 
 5. The three parts seen in the transverse section ; the 
 bundles branching irregularly and obscurely. 
 
 6. The growing apex. Note 
 
 a. The shape. 
 
 b. The sheathing membranous scales. 
 
 c. The position of the aerial branch. 
 Bisect the apex, and upon the cut surface notice 
 
 d. The two or more rather thick projecting bracts. 
 
 e. Beneath these a very small protuberance, the grow- 
 ing point of the stem, sometimes accompanied by 
 smaller lateral protuberances, the rudimentary 
 scales. 
 
 /. Draw the bisected apex. 
 
 D. THE BRANCH (Aerial Stem). Note 
 
 1. The absence of nodes below the whorl of leaves. 
 
 2. The smoothness of the surface. 
 Mount a transverse section. Notice 
 
 3. Ite three parts : 
 
 a. The very narrow cortical region. 
 
 b. 'Yhe fundamental parenchyma, forming the ground 
 work of the section ; the cells appearing empty. 
 
 c. The limited number of fibre-vascular bundles; note 
 
 i. Their arrangement and relative size, 
 
TRILLIUM RECUR VA TUM. 201 
 
 ii. The two areas in each : the light colored por- 
 tion lying toward the outside of the stem, the 
 phloem, the shaded portion lying toward the 
 center of the stem, the xylcm. 
 
 4. Draw the section. 
 
 5. Make a longitudinal section and note the several parts 
 seen in the transverse section. Draw. 
 
 E. THE LEAF. Note 
 
 1. The scale leaves of the rootstock. 
 
 a. The bases of decayed scales at each node. 
 
 b. Younger ones, sheathing the apex of the rootstock 
 and base of the aerial branch. 
 
 Mount a portion of a scale and notice 
 
 c. The parallel veins, and intervening parenchyma. 
 
 d. Numerous dark spots, clusters of raphides. 
 
 2. The foliage leaves of the aerial stem. 
 
 a. The number and arrangement. 
 
 b. The shape. 
 
 c. The particular outline of the apex, and of the 
 base. 
 
 d. The short stalk, petiole, if present. 
 
 e. The distribution of the reins. 
 
 Mount a transverse section from near the base of the leaf, 
 and note 
 
 /. The several parts : 
 
 The colorless epidermis. 
 
 The reins, the largest projecting on the lower 
 side ; each containing 
 
 iii. A fibro-vascular bundle, having the phloem 
 area toward the under side of the leaf ; accom- 
 panied in the largest veins by 
 
202 TRILLIUM. 
 
 iv. Colorless parenchyma. 
 
 v. The darkened (in fresh specimens green) mes- 
 
 ophyll. 
 
 Mount a portion of the epidermis stripped from the upper 
 surface of the leaf, and beside it a portion from the under 
 surface. Note 
 
 g. The numerous dots in that from the lower surface, 
 
 the stomata. 
 
 h. The absence of stomata in that from the upper 
 surface. 
 
 F. THE FLOWER. Note 
 
 1. The several parts arranged in whorls. 
 
 a. The outer whorl of three sepals, constituting the 
 calyx. 
 
 b. The second whorl of three petals, constituting the 
 corolla. 
 
 c. The third and fourth whorls of three stamens each, 
 constituting the androecium, 
 
 d. The innermost whorl of three partly united carpels, 
 constituting the gynoscium. 
 
 2. That the parts of the flower arise from the broadened 
 extremity of the stem, the receptacle. 
 
 3. The alternation of the parts of each whorl with those of 
 the whorl next to it. 
 
 4. The sepals. 
 
 a. The shape. 
 
 b. The color in a fresh specimen. 
 
 c. The venation. 
 
 d. Draw a single sepal. 
 
 5. The petals. 
 
TRILLIUM RECUR VA TUM. 203 
 
 a. The shape. 
 
 b. The color in a fresh specimen. 
 
 c. The venation. 
 
 d. Draw a single petal. 
 
 6. The stamens. 
 
 a. The several parts of each. 
 
 The stalk or filament, passing into 
 The connective, on the right and left margins 
 of which are borne 
 
 iii. The pollen sacs, or thecce ; the connective and 
 thecae together constituting the anther. 
 
 b. Draw a stamen. 
 
 Mount a transverse section of the filament, along with 
 one of the anther, and note 
 
 c. The filament. 
 
 \. The outline. 
 
 ii. The uniform ground tissue, containing a cen- 
 tral fibrO'Vascular bundle. 
 iii. Draw. 
 
 d. The anther. 
 
 i. The outline of the connective, and character of 
 its tissues. 
 
 ii. The form of the thecce. The mode of burst- 
 ing is often well shown. 
 
 iii. Draw the section 
 
 e. The pollen, escaped from the thecae and appearing 
 as fine particles. Dust some from an anther and 
 examine dry, noting color and pulverulence. 
 
 7. The carpels. 
 
 a. The part's of each. 
 
 i. The enlarged basal portion, bearing a pair of 
 prominent ridges, united with the bases of the 
 other carpels to form the compound ovary. 
 
TRILLIUM. 
 
 ii. The tapering divergent styles. 
 iii. The double wavy crest along the inner face of 
 each style, the stigma. 
 
 b. Draw the three carpels. 
 
 Make a transverse section through the middle of the 
 style ; mount, and notice 
 
 c. The outline, including the stigma. 
 
 d. The central fibro-vascular bundle. 
 
 e. The stigma. 
 
 i. The recurved sides, and deep median groove 
 
 extending in to the central bundle, 
 ii. The velvety papilla clothing its surface. 
 /. Draw the section. 
 
 Mount several transverse sections of varying thickness 
 passing through the middle of the compound ovary, and 
 notice 
 
 g. The three similar parts belonging to the three car- 
 pels of which it is composed, each consisting 
 of 
 
 i. The two prominent ridges or wings. 
 ii. The fibro-vascular bundle lying in the tissue 
 
 between the ridges. 
 
 iii. The sides of the carpel uniting with the sides 
 
 of the adjoining carpels, extending into the 
 
 cavity of the ovary and meeting in the center, 
 
 forming the three placentae. 
 
 iv. The two or more fibro-vascular bundles of the 
 
 placenta. 
 
 v. The rounded ovules in the cavity of each car- 
 pel, borne on the sides of the right and left 
 placentae. 
 h. Draw the section. 
 
 G. THE FRUIT. Notice 
 
TRILLIUM RECUR VA TUM. 205 
 
 1. The sepals still in growing condition. 
 
 2. The withered but persistent petals^ stamens and styles. 
 
 3. The fleshy winged pod, like the young ovary, but 
 larger, inclosing 
 
 4. The seeds. Note 
 
 a. The slender attachment. 
 
 b. The fleshy body on the side of the seed, the stro- 
 phiole, which is an outgrowth of the lower part of 
 
 c. The stalk of the seed, funiculus, extending beyond 
 the strophiole as a ridge on the seed, the rhaphe, 
 and terminating at 
 
 d. The base of the seed, the chalaza. 
 
 e. The shape. 
 
 /. The minutely granular surface. 
 g. Draw a seed. 
 
 Beginning at the chalaza, cut several very thin trans- 
 verse sections, then another transverse section from the 
 middle of the seed, mount, and notice 
 
 //. The thin brown coat of the seed, testa, 
 i. The uniform tissue within, the cells of which are 
 filled with reserve food material, and in the 
 section from the middle of the seed are seen to 
 radiate from the center to the outside. 
 j. In the sections from the base of the seed, the 
 small round spot, between the center of the 
 section and the side next the rhaphe, the embryo. 
 
 MINUTE ANATOMY. 
 
 A. THE ROOT. In a central longitudinal section 
 through the root-tip, note under low power 
 i. The outer looser cells and inner more compact tissue 
 forming the root-cap. 1 
 
 1 It may be difficult to get the region complete. 
 
206 TRILLIUM. 
 
 2. A cluster of small angular cells in the center of the 
 section just behind the root-cap, the primary meristem, 
 forming the growing point. 
 
 3. Originating in the primary meristem, an epidermis-like 
 row of cells of the root proper, the dermatogen, which 
 is continuous with the epidermis .of the surface of the 
 root. 
 
 4. The central cylindrical mass of cells, to become the 
 fibro-vascular column, the plerome. 
 
 5. The region of cells between the plerome and dermato- 
 gen or epidermis, to become the cortical portion of the 
 root, the periblem. 
 
 6. The branching root-hairs and their relation to the 
 epidermal cells. 
 
 7. Draw the section, showing the regions above noted. 
 Make a transverse section of the root at its wrinkled 
 
 part. Under low power, notice 
 
 8. The peripheral portion of two or more rows of rounded 
 cells. 
 
 9. The underlying large-celled tissue, with delicate dis- 
 torted walls, often torn in sectioning. 
 
 10. The outer portion of the core, with rounded cells 
 becoming smaller as they lie nearer 
 
 11. The circular axial part of the core, the fibre-vascular 
 bundle, containing several large vessels arranged in 
 four or more short radiating rows. 
 
 Use a high power, and notice 
 
 12. The surface row of cells, the epidermis, slightly or not 
 at all differing from 
 
 13. The cells beneath the epidermis, the hypoderma. 
 
TRILLIUM RECURTATUM. 207 
 
 14. The very thin walls of the loose tissue. 
 
 15. The thickened walls of the outer part of the core, 
 and the intercellular spaces at the angles. 
 
 1 6. Draw a portion of these several tissues of the root. 
 
 17. The somewhat irregular row of thickened, slightly 
 colored cells, the bundle sheath, usually with an evident 
 middle lamella in the walls. 
 
 1 8. The fbro-vascular bundle. 
 
 a. Immediately within the bundle-sheath a row of 
 thin-walled cells, the pericambiitm? 
 
 b. The radial rows of large vessels, larger toward the 
 center, smaller toward the periphery. 
 
 c. The intermediate groups of sieve tissue. 
 
 d. The thin-walled cells of the center of the bundle. 
 f. Draw the nbro-vascular bundle and bundle-sheath. 
 
 Make several longitudinal sections through the core of 
 the root ; identify and study 
 
 19. The several tissues seen in transverse section, drawing 
 a few cells of each. 
 
 B. THE ROOTSTOCK (Subterranean Stem). Make a 
 transverse section, mount in strong potassic hydrate, and 
 notice 
 
 1. The row of epidermal cells with brown outer walls. 
 
 2. The parenchyma tissue within, filled with starch, and 
 forming the mass of the rootstock. 
 
 3. Draw a few cells of epidermis, and of adjoining paren- 
 chyma. 
 
 4. The fibro-vascular bundles, cut at all angles, even longi- 
 8 Sometimes absent in old roots by having become permanent tissue. 
 
208 TRILLIUM. 
 
 tudinally. Owing to the difficulty of obtaining good 
 sections, and the interference of the starch, the further 
 study of the bundles is deferred till they are reached in 
 the aerial stem. 
 
 Cut a thin slice from the surface of the rootstock, and 
 under low power, notice 
 
 5. The shape of the epidermal cells, and absence of sto- 
 mata. Draw. 
 
 Make a longitudinal section through the growing tip in 
 the plane of the branch, and note 
 
 6. The sheath composed of one or more sets of thickened 
 and partly coalesced bracts. These bracts may be 
 detected in various stages of growth, all originating 
 behind 
 
 7. The growing point. 
 
 8. The growing tips of rudimentary roots and branches. Note 
 the exogenous development of a branch, all the tissues 
 of the stem entering into it, and the endogenous devel- 
 opment of a root, distinct from the tissues of the stem 
 and pushing its way through them. 
 
 C. THE BRANCH (Aerial Stem). In a transverse section, 
 with a low power, notice 
 
 1. The single row of epidermal cells. 
 
 2. The loose, round-celled fundamental parenchyma, with 
 large intercellular spaces. 
 
 3. The fibro-vascular bundles, consisting of 
 
 a. The light colored portion, phloem. 
 
 b. The shaded portion, xylem. 
 Under high power notice 
 
 4. The epidermis and hypoderma. Note 
 
TRILLIUM RECUR VA TUM. 209 
 
 a. The thickness of the different walls. 
 
 b. Draw. 
 
 5. ^^ parenchyma of the center of the stem. Note 
 
 a. The shape of the cells. 
 
 b. The thinness of the walls. 
 
 c. The large intercellular spaces, 
 if. Draw. 
 
 6. 'Y\\z fibro-vascular bundle. Note 
 
 a. r Y\\z phloem, consisting of angular cells of various 
 sizes; the smaller, conducting cells or bast paren- 
 chyma, the larger, the sieve tissue. 
 
 b. The xylem, in the smaller bundles of less area than 
 the phloem, but in larger bundles greater, and 
 spreading out on either side the phloem, until, in 
 some cases, it entirely surrounds it.' It is made 
 up of 
 
 i. The vessels of various sizes, and 
 
 ii. Interspersed among the vessels and extending 
 
 out on the axial side, rather angular cells, the 
 
 wood parenchyma. 
 
 7. The absence of meristem cells between xylem and 
 phloem, thus forming a closed bundle. 
 
 8. Draw a small and a large bundle. 
 
 Take a longitudinal section through the center of the 
 stem and notice 
 
 9. The several tissues seen in transverse section. 
 
 a. The epidermal and hypodermal tissues. Draw. 
 
 b. The central parenchyma. Draw. 
 
 3 Forming the external sheath (Prantl and Vines, Text-book, p. 58), 
 which is probably but a special development of the surrounding cells of 
 the fundamental system. 
 
210 TRILLIUM. 
 
 c. The several tissues of the bundle. 
 
 i. The phloem, of long, thin-walled, uniform 
 
 cells. Draw, 
 ii. The vessels, of various sizes and kinds. Draw 
 
 some of each. 
 
 iii. The wood parenchyma, considerably like the bast 
 parenchyma, but in its best development with 
 thicker walls, and more evident somewhat 
 oblique end walls. Draw. 
 
 Strip some epidermis from the surface of the stem, and 
 under low power, notice 
 
 10. The shape and arrangement of the cells, and of the 
 stomata. Draw. 
 
 D. THE LEAF. Make a vertical section near the middle 
 of a foliage leaf, at right angles to the principal veins, and 
 notice 
 
 1. The row of colorless epidermal cells bounding the upper 
 and lower surfaces. 
 
 2. Here and there transverse sections of the veins. Note 
 the depression above, and the convexity below the 
 larger veins. 
 
 3. The mesophyll. Note 
 
 a. The layer of closely set cells along the upper side, 
 palisade parenchyma. 
 
 b. The loose irregular tissue on the lower side, spongy 
 parenchyma. 
 
 Under high power, notice 
 
 c. The shape and position of the cells of the palisade 
 parenchyma. 
 
 d. The shape of the cells of the spongy parenchyma 
 and the numerous intercellular spaces. 
 
 e. Contents of the mesophyll cells. 
 
TRILLIUM RECUR VA TC'.V. 2 1 1 
 
 4. The epidermis. Note 
 
 a. The shape and irregularity of the cells on the 
 upper side of the leaf. 
 
 b. The shape and irregularity of the cells on the 
 lower side, together with the shape of 
 
 c. The numerous stomata in transverse section, when 
 cut through the middle, and when through the 
 ends. 
 
 5. Draw a part of the mesophyll and epidermis, extend- 
 ing from one side of the leaf to the other. 
 
 6. The reins. Selecting a vein of moderate size, note 
 
 a. The small epidermal cells on the upper side, and 
 the large ones on the lower side, both more thick- 
 ened and regular than elsewhere on the leaf. 
 
 b. The fibro-rasculiir bundle, with the xylem area 
 toward the upper side, and the phloem area toward 
 the lower side 4 : sometimes with 
 
 c. Fundamental parenchyma interposed between the 
 bundle and the epidermis on either side. 
 
 d. Draw a vein. 
 
 Strip some epidermis from the upper side of the leaf, 
 and some from the lower side, and notice 
 
 7. The shape and arrangement of the cells of the two sur- 
 faces, and the abundance of stomata. Draw. 
 
 E. THE FLOWER. 
 
 i. The sepals. Make a transverse section through the 
 middle of a sepal, and notice 
 
 a. The several parts and tissues seen in the leaf. 
 Draw. 
 
 4 Note how this follows from the relative positions of xylem and 
 phloem in the stem. 
 
ii2 TRILLIUM. 
 
 Strip some epidermis from the upper and lower sides, 
 and notice 
 
 b. The shape of the cells, and presence or absence of 
 stomata in each. Draw. 
 
 2. The petals. Make a transverse section through the 
 middle of a petal, and notice 
 
 a. The several parts seen in the leaf. Draw. 
 
 Strip some epidermis from the upper and lower sides, 
 and notice 
 
 b. The shape of the cells and presence or absence of 
 stomata in each. Draw. 
 
 3. The stamens. Make a transverse section through the 
 middle of a filament, and at the same time through the 
 middle of the anther, and notice 
 
 a. The parts of the filament. 
 
 i. The epidermis, with a minutely sinuous out- 
 line to the free surface. 
 
 ii. ^ht parenchyma beneath. 
 
 iii. The central fibro-vascnlar bundle, consisting 
 largely of xylem, with only a few small groups 
 of scattered phloem cells on the more convex 
 (outer) side. 
 
 b. Draw part of the filament. 
 
 c. The connective, with tissues like those of the fila- 
 ment. 
 
 d. The theca, consisting of 
 
 i. The two valves usually broken away at the 
 
 tips, springing from 
 ii. The base which merges into the connective. 
 
 e. The wall of the thecal valves. Note 
 
 i. The epidermis, like that of the filament but 
 with numerous stomata, seen in transverse 
 section. 
 
TRILLIUM RECUR VA TUM. 2 1 3 
 
 ii. The cndothecium, having its cells provided with 
 
 transverse thickenings, 
 iii. The broken cells at the tips, corresponding to 
 
 the broken cells at the middle of the base. 
 /. The base of the theca. Note 
 
 i. The arrangement of the spiral cells, 
 ii. The median cavity and its extent. 
 g. Draw a theca in outline, and fill in a portion of the 
 
 tissues. 
 //. The pollen spores. Note 
 
 i. The surface of the wall, its roughness, and 
 the simple, large, round or oblong spots to be 
 seen upon some spores. 
 The wall in optical section. 
 Draw. 
 
 Burst some spores by pressing on the cover glass. Note 
 iv. The empty outer layer of the wall, extine. 
 v. The remainder of the spore, still enveloped by 
 
 the thin intine, roughened like the extine. 
 vi. The contents from broken spores, with minute 
 granules. 
 
 \. The carpels. In a transverse section through the style, 
 notice 
 
 a. The epidermis and parenchyma like that of the fila- 
 ment of the stamen. 
 
 b. The fibro-vascular bundle with apparently no 
 phloem, elongated to embrace the cleft of the 
 stigma. 
 
 The stigmatic surfaces, covered with papillae. 
 
 In some of the pollen spores lodged upon the 
 
 papillae, the developing pollen tubes may be 
 
 detected. 
 
 Illustrate with drawings. 
 
214 TRILLIUM. 
 
 In a transverse section through the compound ovary notice, 
 under low power, 
 
 f. The uniform, continuous epidermis. 
 
 g. The loose parenchyma tissue of the wings and walls. 
 h. The fibro-vascular bundles under the sinus between 
 
 each pair of wings, and the groups in the placen- 
 tae. The latter give off branches to 
 /. The ovules, placed back to back in the ovarian 
 cavities. Note 
 i. The thick stalk, funiculus, joined to the side 
 
 of the ovule, quite inverting it (anatropous]. 
 ii. The two coats of the ovule, the inner protruding 
 
 from the outer, 
 iii. Draw. 
 
 iv. If a section passing through the center of an 
 ovule has been obtained, note the nucellus 
 within the inner coat, and 
 v. In the center of the nucellus the small embryo 
 
 sac. 
 
 vi. Draw. 
 
 Under high power, notice 
 / The epidermis and loose parenchyma at the base 
 
 of a wing. Draw. 
 k. The nbro-vascular bundle of the wall, showing a 
 
 little phloem only on the outer side. Draw. 
 /. The parenchyma and fibro-vascular bundles of the 
 
 placentae. Draw a part. 
 
 m. Where the section has passed through the center 
 of an ovule, note the similarity of the cells of all 
 the parts. Draw. 
 
 F. THE FRUIT. So little change has taken place in the 
 growth of the fruit that it is only necessary to study the 
 minute anatomy of 
 
TRILLIUM RECUR VA TUM. 2 1 5 
 
 i. The seed. Make several sections in succession from 
 the base of the seed, and an additional section from the 
 middle, all at right angles to the longer axis of the 
 seed. Note in the latter, under low power, 
 
 The colorless tissue, filled with reserve /<?#</ mate- 
 rial, radiating from the center of the seed. 
 The thin brown testa. 
 
 The large-celled tissue of the strophiole, through 
 the middle of which passes a fibre-vascular bundle 
 belonging to the funiculus. 
 In the sections from the base of the seed, note 
 J. The group of small cells lying in a cavity on one 
 
 side the center, the section of the embryo. 
 Under high power, notice 
 
 e. The several sections of the embryo. Draw. 
 In the section from the middle of the seed, notice 
 /. The colorless tissues of the center. 
 g. The tissues of the testa. 
 
 i. The outer layer of oblong cells. 
 ii. An inner layer of more elongated cells. 
 iii. Within this, very delicate cells, not easily 
 made out. 
 h. Draw some of the colorless cells, with adjoining 
 
 testa. 
 
 /. The tissue of the strophiole. Draw. 
 
 Take a surface slice from the seed, and notice 
 
 j. The shape of the surface cells. Draw. 
 
 ANNOTATIONS. 
 
 The most notable advance in Trillium, so far as its 
 gross anatomy is concerned, is the development of a 
 
2i6 TRILLIUM. 
 
 complete flower. 5 The so-called flower of Atrichum 
 differs essentially from a true flower in bearing the pri- 
 mary sexual organs (antheridia and archegonia) directly 
 upon the axis of the flower. In true flowers asex- 
 ual spore structures first arise in the shape of pol- 
 len spores and embryo sac, which in turn give rise to 
 the primitive sexual organs as naked cells within these. 
 The first true flowers are met with in Pinus, in which 
 they have no envelopes ; in Avena there is either no 
 perianth, or a very poorly developed one, just as we 
 choose to regard the palet and lodiculesas such or not ; 
 but in Trillium there is a typical perianth. The flower 
 is composed of sets of modified leaves symmetrically 
 clustered at the apex of a short axis. The outermost 
 and lowest whorl (calyx) of leaf-like sepals, a second 
 whorl (corolla) of colored petals, then two whorls 
 of stamens (andrcecium), and a central and uppermost 
 whorl of carpels (gynoecium), all standing upon the 
 broadened apex of a branch (receptacle) may be taken 
 to fairly represent a typical flower. The order given 
 not only expresses the order of occurrence upon the 
 receptacle but also the order of development ; and the 
 type number, three, so characteristic of monocotyle- 
 dens, should be borne in mind (see fig. i). 
 
 The perianth is an arrangement for protection both 
 in bud and blossom, 6 while in the latter stage the cor- 
 olla becomes in addition a device for attraction. 7 
 
 5 For a concise account of the homology and nomenclature of the 
 parts of a flower see Sachs, Text-book, 2nd Eng. ed. , p. 490. 
 
 6 Cf.Kerner, Flowers and their Unbidden Guests. 
 
 7 Cf. Gray, Struct. Bot., p. 215, etseq.: Darwin, Pert, of Orchids ; 
 Effects of Cross and Self-fertilization ; Forms of Flowers etc. 
 
TRILLIUM RECUR VA TUM. 2 1 7 
 
 While this is generally true throughout phanerogams, 
 there are cases in which the calyx becomes attractive, 
 and other cases in which the calyx and corolla have so 
 far lost their original functions that they neither attract 
 nor protect. 
 
 In the blended carpels, forming the pistil which in- 
 closes the ovules, we have the characteristic feature of 
 angiosperms as distinguished from gymnosperms. In 
 Avena the ovule is adherent to the wall of the ovary, 
 but in Trillium it is distinct; the whole after fertilization 
 forming the fruit with its inclosed seeds. Each carpel is 
 an infolded leaf, bearing the ovules upon its edges 
 (see fig. 11). Each should normally, then, contain two 
 rows of ovules, corresponding to the right and left 
 margins of the leaf, as in fact is the case in Trillium. 
 These lines of attachment, the theoretical leaf margins, 
 are known as placentae. The upper part of the carpel- 
 lary leaf is generally modified to form a long or short 
 style, while the stigma is a surface formed of cells se- 
 creting a viscid fluid, and more or less modified for the 
 reception and retention of pollen. 8 
 
 The nucellus is the part of the ovule to appear first, 
 followed by the inner and outer integuments in the order 
 named (basipctal). Concerning the homology of the 
 ovule there has been and still is much discussion, and the 
 student desiring to pursue the subject must look to its 
 extensive literature. 9 The anatropous ovule of Tril- 
 
 8 For discussion of the pistil and carpel, and references to the litera- 
 ture of the subject, see Gray, Struct. Bot., pp. 166 (with footnotes), 259, 
 et seq. 
 
 9 Gray, Struct. Bot., pp. 267, 282; Eichler, Bluthendiagramme, 
 part II, page xv; Warming, De 1'Ovule, Ann. Sci. Nat., ser. 6, v, p. 
 177 ; Van Tieghem. op. cit., ser. 5, xii, p. 312 ; Sachs, Text-book, 2nd 
 Eng. ed., pp. 492, 570, etc, 
 
218 TRILLIUM. 
 
 Hum may be mentioned as by far the most common 
 form.. 
 
 As in Adiantum, the main axis of Trillium is subter- 
 ranean, horizontal and thickened, forming a rootstock, 
 a protective measure which in this case is correlated 
 with spring blooming and a long period of rest. The 
 aerial part of Adiantum, however, is a leaf, while in 
 Trillium it is a branch, the " root-leaves " being 
 reduced to membranous scales on the rootstock. A 
 single branch (rarely two) is sent above ground each 
 season, and a series of corresponding annual scars may 
 frequently be seen upon the stem. In the meantime 
 the terminal bud of the latter continues to develop 
 and to thrust its way through the soil, protected in 
 this root-like habit by a special modification of bud- 
 scales. 
 
 Probably the most exceptional character of Trillium 
 is the venation of its foliage leaves, which is of the 
 netted type, instead of the parallel venation most 
 characteristic of monocotyledons, as in Avena. Among 
 net-veined leaves they are palmate, a type which pro- 
 duces a broad expanse of surface, very favorable for the 
 accomplishment of leaf work. In this way Trillium has 
 secured a large exposure of surface to air and sunlight 
 for a plant so low in stature, and generally deeply sunk 
 in vegetable debris. 
 
 The primary root-structure is quite uniform in all 
 plants, consisting of epidermis (or a piliferous layer), 
 cortical parenchyma, and a central nbro-vascular cylin- 
 der. In the central cylinder xylem and phloem masses 
 alternate with each other, the intervening spaces being 
 occupied by parenchyma (forming a radial bundle) ; sur- 
 
TRILLIUM RECUR VA TUM. 219 
 
 rounding all is a layer of parenchyma, the pericambium, 
 and outside of this a single layer of modified cortical 
 cells, the bundle sheath or endodermis. Rootlets of 
 most cryptogams originate from the bundle sheath, 
 while in phanerogams they usually come from the peri- 
 cambium. 10 In the radiating lines of tracheary vessels 
 it will be noticed that the larger vessels are toward the 
 center, the smaller spiral vessels being peripherally 
 placed, thus reversing the order of the stem. 11 
 
 The stem is very much modified by becoming a food 
 reservoir. The epidermis is poorly limited, often 
 scarcely distinguishable from the adjacent cortical 
 parenchyma ; the parenchyma of the fundamental 
 system is greatly developed and filled with starch ; 
 while the fibro-vascular bundles are reduced and 
 irregular in their course. In most cases the bundles 
 bend outwards, and such are evidently leaf-traces, 1 * 
 though they have lost all definite connection with the 
 accompanying scale-like leaves. 
 
 The terminal bud of the stem is large and its parts 
 very distinct. It is taken to represent in our series a 
 typical terminal bud of phanerogams. A section 
 reveals the fact that the growing point (piinctum vege- 
 tationis) consists of a group of cells, in place of the 
 single apical cell of cryptogams, and the forming tis- 
 sues diverge from it in well defined lines. The three 
 typical regions of the stem originate from different 
 regions of this primary meristem, so that they do not 
 
 10 Prantland Vines, Text-book, p. 51; Strasburger, Bot. Pract., p. 276. 
 
 11 Cf. Goodale, Physiol. Bot., p. no, et seq. ; Prantl and Vines, Text- 
 book, p.5i;DeBary, Comp. Anat., p. 348. 
 
 12 Cf. Prantl and Vines, Text-book, p. 46; Goodale, Physiol. Bot., p. 
 125; DeBary, Conip. Anat., p. 233. 
 
220 TRILLIUM. 
 
 have a common origin, but are distinct from the first. 
 Lateral members soon appear as small protuberances, 
 which are rudimentary leaves, branches, or roots, those 
 nearest the apex being the youngest. The axis 
 remains so short that the lower leaves overlap the 
 growing point, and in the case of this underground stem 
 thicken and coalesce at their tips, forming a continuous 
 and firm sheath, thus performing the same office of pro- 
 tection for the rootstock that the root-cap does for 
 roots. In the same Trillium bud may be seen the 
 essentially different mode of development of the root 
 and branch, the former being endogenous and pushing 
 its way through the overlying tissues, the latter exog- 
 enous, 18 blending with the surface tissues of the stem. 
 
 The branch, or aerial stem, is remarkable for its sin- 
 gle long internode. The fibro-vascular bundles are 
 rather poorly developed, the monocotyledonous stem 
 bundle being more typically represented in Avena. In 
 Trillium, however, are seen such monocotyledonous 
 characters as the isolation of the bundles within an 
 abundant fundamental parenchyma, the well-marked 
 phloem and xylem areas with no intervening cambium 
 (closed bundles), and an occasional development of an 
 external sheath. 14 
 
 The histology of the leaf is in general much the 
 same as in the majority of leaves ; it differs from Avena 
 in the presence of a much better developed mesophyll. 
 A broader expanse of leaf tissue necessitates a greater 
 branching of the supporting and conducting fibro-vas- 
 cular system, and a better differentiation of leaf sur- 
 
 18 Prantl and Vines, op. cit., p. 23. 
 14 Prantl and Vines, op. cit., p. 58. 
 
TRILLIUM RECCKTA ruM. 2*1 
 
 faces. Hence the palisade and spongy parenchyma 
 are quite distinct, and the large intercellular spaces of 
 the latter have more frequent connection with the 
 outer air through stomata. The fact that in the 
 fibre-vascular bundles of leaves the xylem is always on 
 the upper side, and the phloem on the lower, should 
 be recognized as necessitated by the relation which 
 they hold to the same regions in the stem. 
 
 In the ovary the distribution of fibro- vascular bun- 
 dles and the relative positions of phloem and xylem 
 are most interesting and suggestive. The single bun- 
 dles in the outer walls have the phloem toward the 
 outside (the lower surface of the carpellary leaf), and 
 the xylem toward the inside. But the inner group of 
 bundles in the ovarian partitions have their arrangement 
 reversed, the phloem being on the inside (toward the 
 center of the flower) and the xylem on the outside 16 
 (see fig. 10). This is readily accounted for by the in- 
 folding of the carpellary leaves (see fig. 1 1). 
 
 The walls of the ovary show also a region of very 
 loose spongy tissue, developed in the mesophyll of the 
 carpellary leaf, and extending into the style, the con- 
 ducting tissue, " which serves as a path of least resist- 
 ance for the penetrating pollen tubes." 18 
 
 15 Cf. Goodale, Physiological Botany, p. 173. 
 
 16 Goodale, Physiol. Bot , p. 172. 
 
SHEPHERD'S PURSE. 
 Capsella Bursa-pastoris Moench. 
 
 PRELIMINARY. 
 
 THIS plant, chosen to represent the highest develop- 
 ment of plant life, is of European origin, but has 
 become abundant in this country and elsewhere, being 
 one of those vigorous foreign species which hasten to 
 take possession of any cleared or cultivated land. It is 
 found everywhere around dwellings, and in fields and 
 waste grounds. It has not only the advantage of uni- 
 versal distribution, but also of continuous growth 
 throughout most of the year, even a few warm days in 
 winter calling it into bloom. One who does not already 
 know the plant can recognize it from the fact that it is a 
 low, quite insignificant herb,varying in height from five to 
 fifty centimeters (two inches to a foot or two), with a ro- 
 sette of rather narrow jagged root-leaves often lying flat 
 upon the ground, much smaller scattered stem-leaves, 
 and very small white flowers constantly opening at the 
 summit of the branches, and producing small triangular 
 rather heart-shaped pods below (see fig. 6). It is most 
 abundant in spring and early summer, but can be found 
 in bloom throughout the warm months, and may be 
 grown in the green-house for use in winter. 
 
CAPSELLA BURSA.PASTORIS. 223 
 
 The materials needed for studying are alcoholic (or 
 fresh) specimens of roots, stems, leaves, flowers, and 
 pods ; fresh specimens of flower buds ; and potassic 
 hydrate. 
 
 LABORATORY WORK. 
 GROSS ANATOMY. 
 
 A. GENERAL CHARACTERS. Note 
 
 1. The main axis, consisting of a root and stem. 
 
 2. Three kinds of branches : 
 
 a. One on the root, rootlets. 
 
 />. Another on the stem and simply repeating it, long 
 
 or very short, or represented by small buds. 
 f. The third on the upper part of the stem, each 
 
 bearing a single flower, pedicels. 
 
 3. The position of the stem branches with reference to 
 the stem leaves, axillary. 
 
 4. The nodes and internodes of the stem, as indicated by 
 the insertion of the leaves. 
 
 5. The absence of lateral appendages on the root or its 
 branches ; those of the stem and its branches appear- 
 ing as foliage and flower parts. 
 
 6. The absence of leaves or bracts subtending the pedi- 
 
 cels. 
 
 B. THE ROOT. Clean thoroughly, immerse in water 
 over a dark surface, and note 
 
 1. The arrangement of the branches (rhtzotaxy). 
 
 2. The thickened whitish tips of uninjured rootlets. 
 
 1 A notable peculiarity of the order Cruel/era, of which Capsella is a 
 member, 
 
224 SHEPHERD* S P URSE. 
 
 3. Color as contrasted with that of the growing stem. 
 
 4. The root-hairs near the tips of rootlets. 
 
 Make transverse and longitudinal sections of a medium 
 sized root and note the presence and relative importance of 
 
 5. The three tissue regions : 
 
 a. The thin peripheral or cortical region. 
 
 b. The large axial or central cylinder, in which radi- 
 ating lines formed by large ducts can usually be 
 seen in the transverse sections. 
 
 c. A region of loose colorless cells between the other 
 two regions. 
 
 Peel the outer layers from a branching root, and notice 
 
 6. The axis of each rootlet remains attached to the axis 
 of the main root. 
 
 C. THE STEM. Note 
 
 1. Mode of branching. 
 
 2. Surface markings. 
 
 3. The relative lengths of internodes. 
 
 4. Axillary branches or buds. 
 
 Make a transverse section and note 
 
 5 . Three regions : 
 
 a. The peripheral or cortical region. 
 
 b. The narrow median or fibro-vascular region. 
 
 c. The axial or pith region? 
 
 6. The fibro-vascular bundles. Note 
 
 a. Shape and relative size. 
 
 b. The cut ends of the tracheary vessels, as holes 
 through the bundles. 
 
 * Not present in the root. 
 
CAPSELLA BURSA-PASTORIS. 225 
 
 7. Draw the section. 
 
 Make a longitudinal section through a branch and leaf- 
 bearing node, and note 
 
 8. The three regions, as well as 
 
 9. Their relation to the leaf and branch. 
 10. Illustrate with diagram. 
 
 D. THE LEAF. Note 
 
 1. Two sorts of leaves : 
 
 a. Root-leaves, clustered at the base of the stem. 
 
 b. Stem-leaves. 
 
 2. Leaf arrangement (p/iy/lotaxy). Observe that an imagi- 
 nary line connecting the insertions of successive stem 
 leaves is a spiral. Discover the number of times the 
 spiral encircles the stem, and the number of leaves it 
 passes, before reaching a leaf standing directly over the 
 first. 3 
 
 3. Leaf parts ; in the root-leaves a blade and leaf-stalk or 
 petiole, in the stem-leaves simply a sessile blade. 
 
 4. Leaf shapes and sizes, the great variety. Draw a series 
 of the most characteristic. 
 
 5. Leaf surfaces j differences between the upper and 
 lower. Notice 
 
 a. Simple hairs. 
 
 b. Stellate hairs. 
 
 6. Distribution of the veins, and their relation to the teeth. 
 
 7. The uncoiling of the spiral threads, when the leaves are 
 broken by careful stretching. 
 
 3 The student may find it easier to substitute a thread for the imagi- 
 nary line, and must also allow for any twisting of the stem. 
 
226 SHEPHERD' S P URSE. 
 
 E. THE FLOWER. Note 
 
 1. The four sets of organs and the number of parts in each. 
 
 2. The receptacle, the enlarged end of the stem. 
 
 3. The sepals. 
 
 a. The number of whorls. 
 
 b. The shape. 
 
 c. The color in fresh specimens. 
 
 d. Draw a single sepal. 
 
 4. 1\& petals. 
 
 a. The number of whorls. 
 
 b. The j^a/*. 
 
 <r. The color in fresh specimens. 
 </. Draw a single petal. 
 
 5. The stamens. 
 
 a. The number of whorls, and number of stamens in 
 each. 
 
 b. The lengths and positions compared with one 
 another. 
 
 c. The position of the long pairs and short single 
 stamens with reference to the petals. 
 
 d. The four greenish elevations on the receptacle, 
 nectaries, alternating with the paired and single 
 stamens. 
 
 c. The filament, to the tip of which is attached 
 /. The anther. Note 
 i. The two theca. 
 ii. The very narrow connective. 
 iii. The lines of dehiscence (best seen in the anther 
 
 of an advanced bud), 
 iv. The shape of apex and base. 
 v. The different appearance of the inner and 
 outer faces. 
 
CAPSELLA BURSA-PASTORIS. 227 
 
 vi. With a needle gently break open the thecae, 
 and, mounting dry, note the abundance, color, 
 and pulverulence of \hz pollen. 
 ,i, r . Draw an uninjured stamen. 
 
 6. The//jf///. In a just opened flower, note 
 
 (7. The shape. 
 
 b. The three parts, stigma, style, and ovary. 
 
 c. The oi'ulfs. 
 
 d. Draw an uninjured pistil. 
 
 7. Construct a diagram (like fig. i) to show the relation 
 of the parts of the flower to each other. 
 
 F. THE FRUIT. Taking the oldest well-formed pod, 
 
 note 
 
 1 . The shape. 
 
 2. The median ridge of each flattened face extending into 
 the persistent style. 
 
 In a transverse section of a pod note 
 
 3. The partition formed by the inward projection of the 
 two placental 
 
 Open a pod by pulling away the two valves from the 
 ridge, and note 
 
 4. The shape of the valves. 
 
 5. The membranous partition. 
 
 6. The seeds. Note 
 
 a. The funiculus and its attachment. 
 
 b. The roughened surface, best seen in dry seeds. 
 
 c. The shape, appearing curved upon itself, campy- 
 lotropous. 
 
 d. Draw a seed showing its attachment. 
 
2 2 8 SHEPHERD' S P URSE. 
 
 At the free end of as old a seed as possible, tear the seed- 
 coats slightly, and by careful pressure force out 
 
 e. The embryo. Make out the relations of 
 
 i. The seed-leaves, the cotyledons. 
 ii. The initial stem, the caulicle. 
 
 f. Draw the embryo. 
 
 In a transverse section across the long axis of the seed, 
 note 
 
 g. The seed-coats. 
 
 h. The cut faces of the two cotyledons, rather flat 
 
 and in contact with each other. 
 i. A section of the caulicle, at the narrower end of 
 
 the section, and lying against the back of one 
 
 cotyledon (incumbent). 
 j. Diagram the section. 
 
 MINUTE ANATOMY. 
 A. THE ROOT. 
 
 i. The rootlets. Remove some of the smallest rootlets, 
 examine with a high power, and note 
 
 a. In complete rootlets, the root-cap. 
 
 b. Behind the root-cap the central cluster of mer- 
 istematic cells, from which diverging rows of cells 
 pass off, gradually merging into 
 
 c. The permanent tissues of the rootlet. 
 
 d. The root-hairs ; the portion of the root on which 
 found. 
 
 e. Make a diagram of the tissues of the root-tip, and 
 also draw some root-hairs accurately. 
 
 Make a transverse section of a very small rootlet, 4 examine 
 
 4 Secondary changes take place so rapidly in the roots of Capsella, that 
 some difficulty may be experienced in finding one with typical primary 
 root structure ; very young rootlets should therefore be selected for exam- 
 ination. 
 
CAPSELLA BURSA-PASTORIS. 229 
 
 with a high power, and note 
 
 /. A peripheral region, consisting of the epidermis, 8 
 
 and a few layers of hypodermal cells. 
 g. A median region of colorless cells, the cortex. 
 //. Within this a single row composed of somewhat 
 smaller, more closely packed cells, the bundle sheath. 
 i. The space inclosed by the sheath entirely occupied 
 by \\\Q fibro-vascular region, in which note 
 i. The two xylem masses, placed with their inner 
 ends of larger cells in contact, thus dividing 
 the region into similar halves (binary]. 
 ii. The two phloem masses, placed right and left 
 
 of the xylem. 
 
 iii. A limited amount of parenchyma, separating 
 the xylem and phloem portions from each 
 other, and both from the bundle sheath. 
 j. Draw the whole section. 
 
 A series of ^transverse sections of larger and larger root- 
 lets will show secondary changes, characteristic of dicoty- 
 ledons, up to 
 
 2. The main shaft. Make a transverse section, examine 
 with a low power, and note 
 
 a. The entire disappearance of epidermis. 
 
 b. The cortical parenchyma. 
 
 c. The fibro-vascular cylinder. 
 Using a high power, note 
 
 d. The cortical parenchyma arranged in radiating lines, 
 from the tangential and radial division of its 
 meristem cells. The outer layers may be com- 
 posed of thin-walled, close set, squarish cells, cork ; 
 within which are often other layers of larger cells, 
 much distorted from the pressure under which the 
 
 5 The epidermis may have disappeared even in a very small rootlet. 
 
230 SHEPHERD'S PURSE, 
 
 root grows. Any of the cortical cells may have 
 thickened walls. 
 
 e. The alternating xylem and phloem masses. In com- 
 parison with the sections under A. i. note 
 
 i. The increased number and irregularity of 
 xylem and phloem rows, making longer and 
 shorter radial rows, quite obscuring the 
 primitive arrangement. 
 
 ii. An almost complete disappearance of inter- 
 vening parenchyma, xylem and phloem being 
 in close contact. 
 
 f. Draw a segment showing the tissues noted. 
 Make a radial longitudinal section, and using a high 
 
 power, 
 
 g. Compare thoroughly with the regions of the trans- 
 verse section. 8 
 
 //. Illustrate with drawings. 
 
 B. THE STEM. Make a transverse section, examine with 
 low power, and note 
 
 1. Three regions : 
 
 a. Cortical region. 
 
 b. Fibro-vascular region. 
 
 c. Pith. 
 
 2. IL\& fibrd-vascular bundles ; shape and relative sizes. 
 Examine with a high power, and note 
 
 3. One row of epidermal cells, with very thick outer and 
 inner walls. Note 
 
 a. The cuticle. 
 
 6 Several sections will be needed to show all the regions of the fibro- 
 vascular area. 
 
CAPSELLA BURSA-PASTORIS. 231 
 
 b. Sections of stomata. 
 
 4. Several rows vl parenchyma cells. 
 
 5. Usually one row of tolerably large, nearly empty paren- 
 chyma cells, the bundle sheath (best distinguished in 
 section from growing plant). 
 
 6. The masses of fibrous tissue rising between the outer 
 
 portions of 
 
 7. The fibre-vascular bunJlcs ; selecting one of the largest 
 of these, note 
 
 a. The arch of bast fibers ; compare this region with 
 the same in smaller bundles. 
 
 b. Beneath the arch a cluster of smaller irregular cells, 
 soft bast. 
 
 c. The trachcary tissue and wood fibers composing the 
 xylem. 
 
 S. The position and extent of the/////, the regularity of 
 the cells and the intercellular spaces. 
 
 9. Draw a segment of the section containing at least one 
 bundle. 
 
 Make a radial longitudinal section, including a fibro-vas- 
 cular bundle, 7 examine with a high power and note 
 
 10. The epidermal cells. 
 
 11. Parenchyma. 
 
 12. Bundle sheath of squarish cells. 
 
 13. The bast fibers, length and nature of walls. 
 
 14. Soft bast, shape and walls. 
 
 15. Tracheary vessels, variously marked. 
 
 1 In a section which passes between fibre-vascular bundles, the same 
 regions will be noted, except that 13, 14, 15, 16 are replaced by abundant 
 
 fibrous tissue. 
 
23 2 SHEPHERD' S P URSE. 
 
 1 6. Wood fibers, length and nature of walls. 
 
 17. Pith parenchyma, character of walls. 
 
 1 8. Draw the various tissues. 
 
 C. THE LEAF. Make a transverse section of a radical 
 leaf at right angles to the midrib, examine with a high 
 power, and note 
 
 1. The epidermis, consisting of one row of empty cells on 
 the upper and under surfaces of the leaf. Observe 
 
 a. Sections of stomata. Draw. 
 
 b. Hairs of various kinds. Draw. 
 
 2. The mesophyll, consisting of 
 
 a. An upper row of oblong cells with longer axis at 
 right angles to the plane of the \zzi, palisade paren- 
 chyma. 
 
 b. A lower region of rounded loosely aggregated cells, 
 spongy parenchyma, with large and small intercel- 
 lular spaces, those in connection with the stomata 
 being especially large. 
 
 3. The fibro-vascular system. In the section of the midrib 
 note 
 
 a. The position of the phloem and xylem areas with 
 reference to the leaf surfaces. 8 
 
 b. The tissues in each as compared with those of the 
 stem bundles. 
 
 In sections of the veinlets note 
 
 c. The tissues that persist. 
 
 4. Draw a transverse section of the leaf, illustrating all 
 the observed facts. 
 
 8 Note how these positions follow from the relative positions of xylem 
 find phloem in the stem, 
 
CAPSELLA BURSA-PASTORIS. 233 
 
 Mount a portion of the epidermis of both surfaces of the 
 leaf, and note 
 
 5. The epidermal tissue. 
 
 a. Shape of the cells. 
 
 b. Hairs of two kinds. 
 
 c. Stomata, comparative abundance on the two sur- 
 faces. 
 
 d. Often dark sheaf-like masses of raphides, torn out 
 from underlying cells. 
 
 e. Illustrate with drawings. 
 
 D. THE FLOWER. 
 
 1. The sepals. Mount a sepal, examine with a high power, 
 and note 
 
 a. Venation. 
 
 b. Epidermal cells, their shape and striation. 
 
 c. Presence or absence of stomata. 
 
 d. Make a drawing, showing these characters. 
 
 2. The petals. Mount a petal, and note 
 
 a. Venation. 
 
 b. Epidermal cells of the tip and base, their shape and 
 striation. 
 
 c. Presence or absence of stomata. 
 
 d. Draw. 
 
 3. The stamens. Make a transverse section through a fil- 
 ament and also through an anther of an advanced bud, 9 
 examine with a high power, and note 
 
 a. The structure of the filament. 
 i. The epidermis, 
 ii. The parenchyma beneath. 
 
 9 This can best be done by making a section of the entire bud. 
 
234 SHEPHERD'S PURSE. 
 
 iii. The fibro-vascular bundle, comparing its tis- 
 sues with those in the stem bundles. 
 
 b. The two theccz, each consisting of two valves. 
 
 c. The wall of the valves, consisting of 
 
 i. The epidermis. 
 
 ii. The endothecium> an elastic inner row of spir- 
 ally thickened cells. 
 
 d. Draw a section of a theca showing its tissues. 
 
 e. The pollen. Note 
 
 i. The surface of the wall. 
 
 ii. The two layers of the wall : the extine col- 
 ored and with thin spots ; the intine thin and 
 colorless. 
 
 By careful pressure upon the cover glass, there can be 
 seen 
 
 iii. The intine unbroken, but protruding through 
 one of the thin spots in the extine, the 
 true character of the wall becoming thus very 
 obvious, 
 iv. The minutely granular contents. 
 
 4. The pistil. Mount a slice from the surface of the 
 stigma and also a transverse section of the ovary, both 
 cleared with potash, and note 
 
 a. The stigma. 
 
 i. Its surface, with pollen tubes sometimes pene- 
 trating it. 
 ii. Draw. 
 
 b. The ovary. 
 
 i. The epidermal cells, 
 ii. The character of the mesophyll. 
 iii. The fibro-vascular bundles, their position and 
 
 tissues, 
 iv. The structure of the placentae. 
 
CAPSELLA BURSA-PASTORIS. 23$ 
 
 v. The structure of the false partition, 
 vi. Draw. 
 
 c. The ovules. 
 
 i. In favorable sections the pollen tubes maybe 
 seen entering the ovules. These are easily 
 recognized, as the tube breaks off some dis- 
 tance from the micropyle. 
 ii. The fibro-vascular bundle of the funiculus 
 
 terminating in the ovule, 
 iii. The two integuments, distinct from each other 
 
 beyond the bend. 
 
 iv. The nucellus, containing a large cavity, the 
 embryo sac, which follows the curve of the 
 ovule. Within the embryo sac 
 v. The embryo, in various stages of development, 
 vi. Draw, showing all the above facts. 
 The following phases in the development of the embryo 
 can not be seen in alcoholic specimens, but may readily be 
 traced in fresh ones by the use of potash as a clearing agent. 
 
 d. The embryo. Mount some cleared ovules from an 
 advanced but unopened bud, press slightly upon 
 the cover glass, and note 
 
 i. The large curved embryo sac. 
 
 ii. In the end of the sac nearest the micropyle, a 
 
 roundish or oblong cell, the oosphere. 
 iii. At the opposite end of the sac, a mass of 
 
 cells projecting into it. 
 
 Mount ovules from an open flower, treat as before, note 
 iv. In place of the oosphere a chain of cells, the 
 pro-embryo, with the basal cell usually much 
 swollen and with a group of cells at the free 
 end of the chain, the forming embryo 
 
 10 The endosperm, which develops rapidly in angiosperms after fertili- 
 zation, is too transient in this case to make out satisfactorily. 
 
236 SHEPHERD'S PURSE. 
 
 From this point the development of the embryo may be 
 traced with greater or less particularity, by examining 
 ovules in various stages of advancement, until the following 
 condition is seen in seeds from a young pod : 
 v. The pro-embryo has disappeared. 
 vi. The embryo nearly fills the embryo sac, the 
 cotyledons beginning almost exactly at the 
 bend, 
 vii. Make drawings illustrating this development. 
 
 E. THE FRUIT. Make a tranverse section through as 
 old a fruit as possible, clear with potash, and note 
 
 1. The nature of the epidermis, mesophyll, fibro-vascular 
 bundles, placentae and partition, compared with that 
 studied in the ovary. 
 
 2. The seed. In transverse sections of seeds note 
 
 a. The testa, its color and structure. 
 
 b. The thin-walled tissue filled with food material. 
 
 c. The cotyledons, the nature of their tissues as com- 
 pared with those of the leaf. 
 
 d. The caulicle, its structure and tissues as com- 
 pared with those of the stem. Draw. 
 
 e. Draw a complete section of the seed, filling in 
 enough of the tissues to indicate their character. 
 
 ANNOTATIONS. 
 
 Capsella very well presents in a compact form the 
 salient features of a dicotyledon. The paired cotyle- 
 dons, net-veined leaves, four-parted flowers, and con- 
 tinuous fibro-vascular zone of the stem, all mark it as a 
 member of this highest group. 
 
CAP SELL A BURSA-PASTORIS. 237 
 
 The primary root continues the plant axis below 
 the surface of the ground in the form of a tap root, and 
 thus enables the plant to take a deep and firm hold 
 upon the soil. Such primary roots are best developed 
 in dicotyledons and gymnosperms, remaining small in 
 monocotyledons and pteridophytes. 
 
 The foliage, instead of being somewhat evenly dis- 
 tributed along the stem and its branches, is largely 
 collected at the surface of the ground in a cluster of 
 so-called root-leaves. The toothed and lobed outline 
 of the leaves with reticulated venation is quite charac- 
 teristic of dicotyledons. In Trillium (an anomalous 
 monocotyledon in this regard) there was presented the 
 palmate type of net-veined leaves, while in Capsella 
 we find the pinnate type, tending to narrower and 
 longer leaf forms. 
 
 An exceptional feature of Capsella (and other 
 Cruciferce) is the entire suppression of bracts in the 
 flower cluster, giving the pedicels (branches) the 
 appearance of originating from the main axis without 
 subtending leaves. 
 
 The structure of the flower is not typical of dicotyle- 
 dons, in which the type would be better expressed by 
 an arrangement like that of Trillium, after substituting 
 five for three as the type number. As a member of the 
 Cruciferce, however, Capsella has two whorls of two 
 sepals each, the lower (outer) being median (in the 
 plane of the axis) and the inner lateral ; one whorl of 
 four petals, alternating with the .four sepals ; two 
 whorls of stamens, the outer and shorter pair lateral, 
 the inner and longer set composed of four stamens, 
 arranged in axial pairs(tetradynamous) ; and one whorl 
 
238 SHEPHERD'S P URSE. 
 
 of two carpels laterally placed. There has been much 
 discussion concerning the cruciferous flower, chiefly as 
 to its six stamens and single whorl of four petals. The 
 most natural explanation seems to be that which 
 makes two the type number throughout, the inner 
 whorl of stamens and the single whorl of petals each 
 becoming four by chorisis. 11 The morphological sig- 
 nificance of the small glands among the stamens at the 
 base of the ovary is uncertain. 12 
 
 The bi-carpellary ovary becomes two-celled by a 
 membranous outgrowth connecting the two opposite 
 parietal placentae. This outgrowth, not being a usual 
 part of the carpels, is considered a false or spurious 
 partition. When the fruit (a silicle) opens, the two 
 valves split away from this false partition, to which the 
 placentae and hence the seeds remain attached. 
 
 No part of vascular plants has so constant a charac- 
 ter as the root. The root-cap and root-hairs, most 
 characteristic root structures, are much alike in all 
 cases. The primary arrangement of the tissues in 
 pteridophytes, gymnosperms, monocotyledons, and 
 dicotyledons is upon the same plan throughout. The 
 original number of xylem and phloem masses is quite 
 limited in dicotyledons, ranging from two of each (bi- 
 nary, as in Capsella) to eight, but is not constant ; while 
 in monocotyledons it is generally larger. In dicotyle- 
 dons and gymnosperms the root increases in thickness 
 by secondary growth which eventually produces great 
 
 11 Gray, Struct. Bot., p. 206, with reference to the views of Eichler, 
 Kunth, Henslow, and others ; Strasburger, Bot. Pract , p. 587 ; Eichler, 
 Flora, 1865, p. 497, and 1869, p. 97 (both with plates) ; Bltithendia- 
 gramme, ii, p. 200, where the literature is cited. 
 
 l * Cf. Hildebrand, Prings. Jahrb., xii, p. 10 ; Mttller, ibid, p 161. 
 
CAPSELLA BURSA-PASTORIS. 239 
 
 changes in the primary structure. Certain of the deli- 
 cate parenchyma cells lying between the xylem and 
 phloem elements undergo repeated division, producing 
 wood and bast tissue. The layer of cambium cells thus 
 begun on either side of the original plate of xylem soon 
 unites with its neighbor at the ends, and forms a closed 
 cambium ring. This ring has the properties of the 
 cambium layer of the stem, as in Pinus, and by means 
 of it the root is enabled to increase in thickness 
 to any extent. It does not, however, as in the 
 stem, produce its phloem exclusively on the outside and 
 xylem on the inside of the ring, but they lie side by 
 side in radiating lines, the number of these lines 
 increasing with the increase in circumference. 18 
 
 The fundamental system in the stem of dicotyle- 
 dons is much more differentiated than is usual in mon- 
 ocotyledons. It is divided into an inner and outer 
 region by the fibro-vascular system, in the latter of 
 which various tissues may be developed, such as col- 
 lenchyma, fibrous tissue, etc. In the case of Capsella 
 the principal modification of the parenchyma of the 
 fundamental system is the development of the abun- 
 dant fibrous tissue (sometimes referred to scleren- 
 chyma), which embraces the xylem of the bundles 
 and arches between the phloem areas. In the fibro- 
 vascular system the chief characters of the dicotyle- 
 donous stem appear. The wedge-shaped bundles are 
 not scattered through the fundamental tissue, but 
 are arranged in a zone concentric with the surface of 
 
 13 On the secondary thickening of roots see DeBary, Comp. Anat , p. 
 473 ; Goodale, Physiol. Bot, p. 113 ; VanTieghem, Ann. Sci. Nat., ser. 
 5, xiii, p. 185. 
 
2 40 SHEPHERD' S P URSE. 
 
 the stem, and inclosing the inner region of the funda- 
 mental tissue, the pith. The parenchyma rays 
 (medullary rays) left between the bundles may be 
 broad or narrow. The arrangement and course of the 
 bundles depend largely upon the position of the leaves. 
 From each leaf one or more bundles enter the stem 
 and passing downward finally become part of the fibro- 
 vascular zone. Transverse sections of the stem often 
 cut across bundles midway in their course from the 
 leaf to the vascular ring, and they then appear as if 
 belonging to the cortex. The bundles are collateral, 
 with a cambium layer between the xylem and phloem, 
 forming the characteristic open bundle of dicoty- 
 ledons. In Capsella a bundle-sheath arches over each 
 bundle, and frequently becomes continuous around 
 the entire fibre-vascular zone." In the xylem the 
 spiral and annular vessels are the oldest and most 
 centrally placed, the dotted ducts, the largest elements 
 of the xylem, occurring nearest the phloem 15 
 
 The leaf shows the general dicotyledonous charac- 
 ters of more contorted epidermal cells and more num- 
 erous and smaller stomata. The fibro-vascular bun- 
 dles are like those of the stem, tracheides replacing 
 other vascular elements in the ultimate ramifications. 
 
 Capsella is so favorable for the study of the 
 development of the embryo, that this very import- 
 ant subject has been deferred until now. It has 
 already been seen how the asexually produced pollen 
 spore (microspore), after falling upon the papillated 
 
 14 Pointed out by Kamienski, in DeBary's Compar. Anat., p. 415. 
 
 15 For stem structure see Prantl and Vines, Text-book, p. 47 ; Bessey, 
 Bot., p. 438 ; Goodale, Physiol. Bot., p. 119. 
 
CAPSELLA BURSA-PASTORIS. 241 
 
 surface of the stigma, develops a pollen-tube and pene- 
 trates the tissues of the style. The rate of descent of 
 the pollen-tube is quite various in different plants. In 
 the style and walls of the ovary there is usually a 
 region of least resistance to penetration, furnished by 
 the delicate " conducting tissue," or the style is 
 frequently tubular (as in Viola). In Capsella, very 
 soon after pollination, an abundance of pollen-tubes is 
 found in the ovarian cavity. Some of them may be 
 seen to have entered the micropyles of the ovules and 
 penetrated to the nucellus. 
 
 The preparation of the ovule for fertilization has 
 been the development, at the apex of the nucellus, of 
 the embryo sac (macrospore), at the micropylar end of 
 which lies the oosphere (embryonal vesicle), accompa- 
 nied usually by two similar masses, the synergidae. At 
 the base of the embryo sac appear three or more free 
 cells, the antipodal cells " of Hofmeister. The six 
 cells which differentiate into the antipodal cells, 
 oosphere and synergidae, constitute a very rudimentary 
 prothallium, 17 which is far more reduced than in gym- 
 nosperms, but corresponds to the primary endosperm 
 of these plants. The endosperm (of most text-books), 
 more properly secondary endosperm, is produced by 
 cell-formation around the nuclei arising from division 
 of the definitive nucleus of the embryo sac. 18 When 
 
 16 Strasburger, Bot. Pract., p. 522, et seq.; Prantl and Vines, Text- 
 book, p. 205. 
 
 17 Sachs, Text-book, 2nd Eng. ed., p. 582, where a fuller account 
 of the changes preliminary to fertilization in angiosperms may be 
 found. 
 
 18 Sachs, Text-book, 2nd Eng. ed., p. 585. 
 
242 SHEPHERD'S PURSE. 
 
 fertilization 19 has taken place a membrane is devel- 
 oped about the oosphere, making it a sexual spore. 
 
 By divisions 20 in one plane the oospore at once 
 extends toward the interior of the ovule as a chain of 
 cells, the suspensor or pro-embryo, the basal cell of 
 which becomes large and bladder-like. The apical cell 
 at the free end of the suspensor, by repeated division 
 in several planes, forms a cell mass, which presently 
 assumes the form of the embryo. 81 The ovule after 
 various changes of minor importance in this connec- 
 tion becomes at last a ripe seed. 
 
 19 For an account of the nuclei of the pollen spore and oosphere, and 
 their union in the fertilizing act, see Strasburger, Neue Untersuchungen. 
 
 20 For methods of cell division in the developing embryo of Cap- 
 sella (with figures) see Bessey, Bot. , p. 424 ; Westermaier, Die ersten 
 Zelltheilungen im Embryo von Capsella, Flora, 1876, p. 483. 
 
 21 For further description of the development of the embryo see Gray, 
 Struct. Bot., p. 283 ; Prantl and Vines, Text-book, p. 204 ; Bessey, Bot., 
 p. 423 ; Sachs, Text-book, 2nd Eng. ed., p. 585. 
 
GLOSSARY. 
 
 Ab-stri'c-tiou (ab, off : stringo, / tie). 
 Partial or complete separation by con- 
 traction. 
 
 A-na't-ro-pous (ara, up; Tptww, / 
 turn). Said of an inverted ovule or 
 seed which has the rhaphe extending 
 its whole length. 
 
 Aii-drcB'-ci-uiii larjjp, a male ; OIKO, 
 a house). The stamens of a flower 
 collectively. 
 
 A n mi lus (annulus, a small ring). 
 The elastic ring of cells around the 
 sporangium in ferns. 
 
 A'n-ther tarflrjpos, Jlo-wery). The pol- 
 len-bearing part of the stamen. 
 
 An-ther-i d-i um. pi. aiitheridia 
 (anther; tISos, form). The male or- 
 ^:in of the lower groups, analogous to 
 but not homologous with the anther 
 of phanerogams. 
 
 A'li-ther-o-zoids (anther; ^wor, an 
 animal ; eI6o?, form). The male re- 
 productive bodies developed in an- 
 theridia. 
 
 A'n-tho-tax-y (arOos, a flower ; rafi?, 
 arrangement). The arrangement of 
 flowers in a cluster ; inflorescence. 
 
 Aii-ti'p-o-dal (ii'Ti, over against: 
 rrous, afoot). Said of a group of cells 
 at the end of the embryo-sac furthest 
 from the micropyle. 
 
 A'p-i-oal (apex, the top). At the apex 
 or tip. 
 
 A-po'ph-y-sis (an-6, from ; <u'<ris, na- 
 ture). In mosses, an enlargement of 
 the pedicel at the base of the capsule. 
 
 Arch-e-go'n i-um, pi. archegonia 
 (ap\ij. beginning: -yoi'jj, offspring). 
 
 The female organ of bryophytes and 
 pteridophytes. 
 
 A-re'-o-la, pi. areolaB (areola, a small 
 open space). The spaces in a reticu- 
 lated surface, as in the thallus of 
 Marchantia. 
 
 A s-co-spores. The spores formed in 
 an ascus. 
 
 A s-cus, pi. ascl (a<7<co, a sac). The 
 spore sac of a large group of carpo- 
 phytes. 
 
 A'x-i-al. Relating or belonging to the 
 axis. 
 
 A'x-il (axilla, the arm-pit). The point 
 just above the attachment of a leaf to 
 the stem. 
 
 A x-is (axis, an axle-tree). The cen- 
 tral part or longitudinal support on 
 which organs or parts are arranged. 
 
 Bast (bass). In general, the phloem 
 region of a fibro-vascular bundle : or, 
 specifically, the fibers of the phloem. 
 
 Bract (bractea, a thin plate). The 
 more or less modified leaves of a 
 flower cluster. 
 
 Bry-o'ph-y-ta (,8pwoi', moss ; ^vrdf, a 
 plant). A primary division of plants, 
 named from its principal group, the 
 mosses. Bry'-o-phyte is the English 
 equivalent. 
 
 Bu'l li-form (bulla, a swelling). Said 
 of enlarged or swollen cells. 
 
 Ca 1 lus (callus, a callosity). A hard- 
 ened or thickened place ; technically 
 used of the thickening mass in a sieve- 
 plate, usually appearing as a layer on 
 each side of the plate. 
 
244 
 
 GLOSSARY. 
 
 Ca-ly'p-tra (<a.\vmpa, a. cover). In 
 mosses, the hood which covers the 
 capsule. 
 
 Ca'-lyx (calyx, a cup}. The outer en- 
 velope of a flower, composed of sep- 
 als. 
 
 Ca'm-bi-form. Resembling cam- 
 bium. 
 
 Ca'm-bi-um (cambio, / exchange). 
 The meristem cells of an open fibro- 
 vascular bundle, lying between the 
 phloem and xylem, which retain the 
 power of division. 
 
 Cam-py-lo't-ro-pous (/caju.7rij, bend- 
 ing; rpeirw, / turn\. Said of an ovule 
 or seed which becomes curved in its 
 growth so as to be inverted. 
 
 Ca'p-sule (capsula, a small box). A 
 dry dehiscent seed-vessel (formed of 
 more than one carpel) ; or a similar 
 spore-vessel. 
 
 Ca'r-pei (<cap7r6s, fruit}. The con- 
 stituent leaf of a pistil hence either a 
 simple pistil, or one of the parts of a 
 compound pistil. 
 
 Ca'r-pel-la-ry. Relating to a carpel. 
 
 Car-po-go'-ni-um, pi. carpogonia 
 (/capTTOS, fruit ,-yovr), offspring). The 
 female organ of carpophytes. 
 
 Ca'r-po-phyll (/capwos, fruit ; </>vAAov, 
 a leaf). The carpellary leaf. 
 
 Car-po'pli-y-ta (xapTros, fruit ; <f>vT6v, 
 a plant). A primary division of 
 plants, named from the sporocarp, or 
 spore-vessel, which is the result of 
 fertilization. Ca' r-po-phyte is the 
 English equivalent. 
 
 Cur-y-o'p-sis (xapvoi', a nut ; oi|us, an 
 appearance). A grain ; the seed-like 
 fruit of grasses. 
 
 Cau'-li-cle (cauliculus, a small stem). 
 The initial stem in an embryo. 
 
 Cell (cella, a cell}. The anatomical 
 unit of plant-structure. 
 
 Ce'1-lu-lose (cellulosus, pertaining to 
 a cell}. The primary substance of the 
 cell-wall. 
 
 Chaff. Small dry scales. 
 
 Cha-la'-za (x<xAaa, that which is let 
 loose). The part of an ovule where in- 
 teguments and nucellus are confluent. 
 
 Chlo'-ro-phyll (xAwpos, greenish-yel- 
 low ; ^uAAov, a leaf). The green 
 coloring matter of plants. 
 
 Cho'r-i-sis (xwptffis, a separating). 
 Longitudinal separation into two or 
 more similar parts. 
 
 Ci'1-i-uni, pi. cilia (cilium, an eye- 
 lash). Marginal hairs ; motile proto- 
 plasmic filaments, as those of anthero- 
 zoids. 
 
 Closed bundle. A fibre-vascular 
 bundle containing no cambium. 
 
 Col-la't-er-al (con, together ; latus, a 
 side). Side by side ; used of a fibro- 
 vascular bundle in which the xylenj 
 and phloem are side by side in a radial 
 direction. 
 
 Col-u-me'1-la (columella, a small 
 column). The persistent axis of cer- 
 tain spore-cases, as in mosses. 
 
 Coii-ce'n-tric (con, together; centrum, 
 the center). Technically used of a 
 fibro-vascular bundle whose tissues 
 are arranged concentrically. 
 
 Co ni' di o-phore (conidia ; </>epw, / 
 carry). The stalk upon which co- 
 nidia are borne. 
 
 Co-ni'-tli-um (gonidiutn), pi. conidia 
 (yovr), offspring; eZSos, form). The 
 asexual spores of certain groups. 
 
 Con jn-ga' tion (conjugatus, joined 
 together, paired). The sexual union 
 of similar cells, as in zygophytes. 
 
 Con-iie'ct-ive (connecto, I connect}. 
 The portion of the stamen connecting 
 the thecae. 
 
 Co-ro'1-la (corolla, a small crown). 
 The inner envelope of a flower, 
 within the calyx, and composed of 
 petals. 
 
 Cor-pu's-cu-lum, pi. corpuscula 
 (corpusculum, a little body). The 
 archegonium-like structures in the 
 ovule of gymnosperms. 
 
 Co'r-tex (cortex, the bark). The rind 
 or bark. 
 
 Co'r-ti-cal. Relating to the cortex or 
 bajk. 
 
 Cot-y-le'-doii (KOTV \yStav, a cup-shaped 
 cavity). A primary embryo-leaf 
 borne by the caulicle. 
 
GLOSSARY. 
 
 245 
 
 On'- pule (cupula, a little tub}. The 
 m mma-cup of liverworts. 
 
 Cii' tide icuticula, the skin). The 
 outenno-,1 film or pellicle of the epi- 
 dermis, differing chemically from the 
 remainder of the cell-wall. 
 
 I)T ma -to-gen (5e'p>Aa t skitt ; yetrau, 
 / produce). The layer of nascent 
 epidermis in the meristem of growing 
 points. 
 
 l>i ebo r o moiisiSixa, in tivo ; rinviit, 
 1 cut). Forking regularly by pairs. 
 
 I)i eot y-le'd-o-nous (6is, double; 
 cotyledon). Having two cotyledons, 
 or seed-leaves. 
 
 l)i le'-cious (Si's, double ; OIKO?, a 
 house). Having the two sex-organs 
 borne by distinct individuals. 
 
 K'l-a ter ('Aarjjp, one that expels). 
 Spirally thickened cells within the 
 sporogonia of some liverworts, which 
 in expelling the spores. 
 
 K'ni bry-o ' t>|3pi>of . /art us, or embryo). 
 The young plantlet within the seed. 
 
 Embryo-sac. The cavity, within the 
 nucellus, in which the embryo de- 
 velops. 
 
 Fn do de'rm is it'i'Soy, within: fie'p/^a, 
 the skin). The layer of cells inclosing 
 th > tibro- vascular bundle ; the bundle 
 sheath. 
 
 En do'g e nous (ei'fiof, within; 
 yci'i'aw, I produced. Originating from 
 internal tissues, and penetrating the 
 outer ones. 
 
 K'n do sperm ui-Sor, within ; o-Tre'pjxa, 
 the seed). A parenchymatous tissue 
 developed within the embryo-sac. 
 
 K'n do spore leVfioy, ivithin ; spore). 
 The inner layer of a spore-wall. 
 
 Kn do I hr <! tun (ev&ov, ivithin; 
 theca). The inner wall of the theca. 
 
 Fp-i-de'rm-is (en-i, upon; Se'pfxa, the 
 skin). The outermost layer of special 
 cells covering plant-surfaces. 
 
 E'p-i-phragm (ewi, upon : <J>pa-y/ia, a 
 protection}. In mosses, a membrane 
 covering the orifice of the capsule. 
 
 Ex o'g-e nous ('efw, outside : ytwdu. I 
 
 produce). Originating from outer 
 
 layers of tissue, 
 i: \ .. -.pore (tfw, outside\ spore). 
 
 The outer layer of a spore-wall. 
 K'x tine Dexter, on the outside). The 
 
 outer coat of a pollen-spore. 
 
 l-'i IMT (fibra, a Jiber). A long and 
 slender, thick-walled cell. 
 
 li Inous Composed of fibers. 
 
 Fi bro-va's-cu-lar (fibra, a fiber; 
 vasculum, <t small vessel}. Composed 
 of fibers and vessels ; ffbro-vascular 
 bundles are the strands which make 
 up the framework of the higher 
 plants. 
 
 Fl'l a-ment (filum, a thread}. The 
 stalk of the stamen, supporting the 
 anther ; also the individual threads of 
 algae or fungi. 
 
 Flowering glume. In grasses, the 
 bract which subtends each flower, 
 sometimes called lower palet. 
 
 Frond (frons, a leaf). A name given 
 to the leaves of ferns. 
 
 riiiid:uiirnt:;l tiu-. That outside 
 the fibre-vascular bundles and in- 
 closed by the epidermis, but not in- 
 cluded in either. 
 
 Fu-ni'c-u-lug (funiculus, a slender 
 rope}. The stalk of an ovule or seed. 
 
 Gem' ma, pi. gemmae (gemma, a 
 bud). In bryophytes, many-celled 
 bodies for asexual propagation. 
 
 Glau'-cous (yAavKos, pale green, fray]. 
 Whitened with a bloom, like that on 
 a cabbage-leaf. 
 
 Glume (gluma, a husk). A chaff-like 
 bract belonging to the inflorescence 
 of grasses ; the outer glumes subtend 
 the spikelet ; the flowering glume is 
 the bract of the flower. 
 
 Glu'ten (gluten, glue}. A general 
 term for the glue-like products of 
 plants, especially of seeds. 
 
 Grain. A seed-like fruit, like those of 
 grasses, with pericarp adnate to the 
 seed ; also any small rounded body, 
 as of starch or chlorophyll. 
 
 Growing point (punctum vegeta- 
 
246 
 
 GLOSSARY. 
 
 tionis). The group of meristem cells 
 at the growing tip of an organ, from 
 which the various tissues arise. 
 Gy-noe'-ci-um (yvv>7, a female ; OIKOS, 
 a house). The pistil, or collective 
 pistils, of a flower. 
 
 Haus-to'-ri-a (haustor, a drinker). 
 The absorbing organs of certain para- 
 sitic plants. 
 
 Her-ma'pli-ro-dite (ep/u.a<p6SiTos, one 
 ivko is both male and female). Hav- 
 ing both kinds of sexual organs borne 
 together on the same axis. 
 
 Host. The plant upon which parasitic 
 plants [or organisms] develop, and 
 from which they derive their nourish- 
 ment. 
 
 Hy-gro-sco'p-ic (uypo?, ivet ; o-KOTreto, 
 / look out for\. Having an avidity 
 for water. 
 
 Hy-me'n-i-um (uju.rji', a membrane). 
 In fungi, a surface layer of vertical 
 filaments containing or bearingspores. 
 
 Hy'-pha, pi. hyphse (v(fj, a -web). 
 The slender vegetative filaments of 
 fungi which may or may not be 
 woven into a mat (mycelium), or a 
 plant body. 
 
 Hy-po-de'r-ma (UTTO. under; Se'p/ixa, 
 the skin). The thick-walled tissues 
 beneath the epidermis, which serve 
 to strengthen it, but do not belong 
 to the fibre-vascular bundle. 
 
 In-eu'm-bent (incumbo, / lean upon). 
 Leaning or resting upon ; of cotyle- 
 dons, when the radicle is against the 
 back of one ; of anthers, when they lie 
 against the inner face of the filament. 
 
 In-du'-si-xim, pi. indusia (indusium, 
 clothing). In ferns, a cellular out- 
 growth of the leaf covering the clus- 
 ters of sporangia (sori). 
 
 In-flor e's-cence (infloresco, / blos- 
 som). The arrangement of flowers ; 
 or the flowering portion of a plant. 
 
 In ter-ce'1-lu-lar. Between or among 
 the cells. 
 
 In'-ter-node (inter, between ; nodus, a 
 joint). The part of a stem between 
 two nodes. 
 
 In'-tine (inter, on the inside^. The in 
 ner coat of a pollen-spore. 
 
 La'm-i-iia (lamina, a layer). The 
 blade, or expanded part, of a leaf. 
 
 Leaf-trace. The ribro-vascular bun- 
 dles from the leaf which descend into 
 the stem, and sooner or later become 
 blended with its fibre-vascular system. 
 
 L,i'g-ule (ligula, a small tongue). In 
 grasses, a thin appendage at the junc- 
 tion of leaf-blade and sheath. 
 
 L,o'd-i-cule (lodicula, a small cover- 
 let). A small scale in the flower of 
 grasses. 
 
 Ma'c-ro-spore (/Aaxpos, large ; spore). 
 The larger spore of the two kinds 
 produced by certain pteridophytes. 
 
 Me'd-ul-la-ry (medulla, pith). Re- 
 lating to the pith ; medullary rays are 
 the pith-rays which pass outward 
 to the bark between the fibro-vascular 
 bundles. 
 
 Mer-i's-tem (juepi^w, / divide). Tis- 
 sues in a nascent or differentiating 
 state. 
 
 Me's-o-pliyll (/ueVos, middle ; <u'AAor. 
 a leaf). The green or soft tissue of 
 a leaf, supported by the framework 
 and exclusive of the epidermis, called 
 by the older botanists parenchyma. 
 
 Mi'-cro-pyle (juiKpos, small ; TruArj. a 
 gate). The opening left by the in- 
 teguments of the ovule, and which 
 leads to the nucellus. 
 
 Mi'-cro-spore (/ui/cpos, small ; spore). 
 The smaller spore of the two kinds 
 produced by certain pteridophytes. 
 
 Mi'd rib. The central or main rib of 
 a leaf or thallus. 
 
 Mon o-po'-di-al (/adi/os, single ; TTOVS, 
 a foot). Said of a stem consisting of 
 a single and continuous axis (foot- 
 stalk). 
 
 My-ce'-li-um (/U.VKIJS, a mushroom; 
 At?, cloth). The filamentous vegeta- 
 tive growth of fungi, composed of 
 hyphse. 
 
 Naked. Wanting some usual cover- 
 ing. 
 
GLOSSARY. 
 
 247 
 
 Ne'e ta ry (nectarium, a depository for 
 nectar}. The place or appendage in 
 which nectar is secreted. 
 
 Nerve (nervus, a nerve). A simple 
 vein or rib. 
 
 Node (nodus, a joint}. That part of a 
 stem which normally bears leaves. 
 
 Nii-ce'1-lus (nucella, a little kerne!). 
 The mass of the ovule within the in- 
 teguments, sometimes called the nu- 
 cleus. 
 
 Nu-rle'-o-lus (diminutive of nucleus). 
 The sharply defined point often seen 
 in the nucleus. 
 
 Nu'-cle-us (nucleus, a kernel). The 
 usually roundish mass found in the 
 protoplasm of most active cells, and 
 differing from the rest of the proto- 
 plasm in its greater density. 
 
 O-o go'-ni-nm. pi. oogouia tiibr, /i 
 f g ' y v *l, offspring). The female or- 
 gan of oophytes. 
 
 O o'ph y-ta iwor, an egg; <vrof, a 
 plant). A primary division of plants, 
 named, from the mode of reproduc- 
 tion, the egg-spore plants. O'-o-phyte 
 is the English equivalent. 
 
 O'-o sphere (woy, an egg ; atfralpa, a 
 sphere}. The naked female egg-cell; 
 the mass of protoplasm prepared for 
 fertilization. 
 
 O'-o-spore (<ioi>, an egg; spore). In 
 general, the egg-cell after fertilization, 
 and surrounded by a cell-wall ; also 
 specially applied tc the spore formed 
 fn an oogonium. 
 
 Open bundle. A fibre-vascular bun- 
 dle \vhich contains cambium. 
 
 O pe'r-cu-lum, pi. opercula (oper- 
 culum, a cover). In mosses, the ter- 
 minal lid of the capsule. 
 
 O'-va-ry (ovarius, an egg-keeper). That 
 part of the pistil which contains the 
 ovules. 
 
 O'-vule (diminutive of ovum, an egg). 
 The body which becomes a seed after 
 fertilization. 
 
 Pa -let ipalea, chajff"). In grasses, the 
 inner bract of the flower. 
 
 Palisade cells. The elongated 
 
 parenchyma cells of a leaf, which 
 stand at right angles to its surface, 
 and are usually confined to the upper 
 part. 
 
 P;i 1-niate (palma, the hand). Radiat- 
 ing like the fingers; said of the veins 
 or divisions of some leaves. 
 
 Pa'n-i-cle (panicula, a tuft). A loose 
 and irregularly branching flower- 
 cluster, as in many grasses. 
 
 Par-a'ph-y-sis, pi. p;ii -;ipli\ < 
 (irapa, beside ; <i>(7is, nature). Sterile 
 bodies, usually hairs, which are found 
 mingled with the reproductive organs 
 of various cryptogams. 
 
 Pa-re'n chy ma (iropcy^c'w, I pour in 
 beside). Ordinary or typical cellular 
 tissue, i.e. of thin-walled, nearly iso- 
 diametnc cells. 
 
 Parthenogenesis ^jrapfln-os. a. 
 virgin; yeyecric, generation). Com- 
 monly applied to the production of 
 seed without fertilization ; but, strict- 
 ly, the formation of a sexual spore 
 without fertilization. 
 
 Pe'd-1 eel (pediculus, a little foot). 
 The stalk upon which an organ is 
 borne. 
 
 Pe du'n-cle (pedunculus, a little foot}. 
 The general flower-stalk. 
 
 Pe'r-1-anth (irepi, around ' : ai-0?, a 
 flouuer). The floral envelopes, or 
 leaves of a flower, taken collectively ; 
 and an analogous envelope of the 
 sporogonia of certain liverworts. 
 
 Pe'r-i-blem (jrepi'/SArj/xa, a covering). 
 A name given to that part of the mer- 
 istem at the growing point of the 
 plant-axis, which lies just beneath the 
 epidermis and develops into the cor- 
 tex. 
 
 Per-i-ca'm-bi nin (irepi, around ; 
 cambium). In roots, the external 
 layer of the fibro-vascular cylin- 
 der. 
 
 Per-i-chae'-ti-um, pi. perichaetia 
 (Trepi, around ; ^ac'rj, kair^ or leaf). 
 In bryophytes, the leaves or leaf-like 
 parts which envelop the clusters of 
 sex-organs, forming in some cases the 
 so-called flower. 
 
248 
 
 GLOSSARY. 
 
 Pe'r-i-stome (irepi, around ; 0To/u.a, a 
 mouth). In mosses, usually bristle- 
 like or tooth-like structures surround- 
 ing the orifice of the capsule. 
 
 Per-i the' ci-um, pi. perithecia 
 (wept, around ; 0JKtj, a- case). The 
 spore-vessel of certain carpophytes, 
 containing the spore-sacs (asci). 
 
 Pe't-al (Tre'raAoi', a leaf). A corolla 
 leaf. 
 
 Pe't-i-ole (petiolus, a little f oof). The 
 stalk of a leaf. 
 
 Phan-e-ro-ga'-mi-a (<J>af epos, evident ; 
 yajw,os, marriage). A primary division 
 (the highest) of plants, named from 
 their mode of reproduction, the seed- 
 producing plants. Pha' n-e-ro-gam is 
 the English equivalent. 
 
 Phlo'-em (</>Aot6s, the inner bark). 
 The bark or bast portion of a fibre- 
 vascular bundle. 
 
 Phy-co-cy'-aii-ine (^UKOS, sea-weed; 
 KUO.I/OS, dark blue). A bluish coloring 
 matter extracted by water from cer- 
 tain algae. 
 
 Phy'1-lo-tax-y (</>vAAov, a lea/; rafi?, 
 arrangement). Leaf -arrangement. 
 
 Pi'n-na, pi. pinnae (pinna, a feather). 
 One of the primary divisions of a 
 pinnate leaf, as in ferns. 
 
 Pi'n-nule (pinnula, a little feather). 
 One of the divisions of a pinna. 
 
 Pi's-til (pistillum, a pestle). The fe- 
 male organ in phanerogams. 
 
 Pit. A thin place, or pit-like depres- 
 sion, left in the thickening of a cell- 
 walk 
 
 Pla-ce'n-ta, pi. placentae (placenta, 
 a cake). That portion of the ovary 
 which bears the ovules. 
 
 Ple'-rome (TrArjpw/aa, that which fills). 
 A name given to that part of the mer- 
 istem near the growing points of the 
 plant-axis, which forms a central shaft 
 or cylinder and develops into the 
 axial tissues. 
 
 Plu'-mule (plumula, a small, soft 
 feather). The terminal bud of the 
 embryo above the cotyledons. 
 
 Pod. A dry, several-seeded, dehiscent 
 fruit; or a similar spore-case. 
 
 Po'l-len (pollen, fine flour). The 
 spores developed in the anther. 
 
 Pol-lin-a'-tion. The transfer of pol- 
 len to its stigma. 
 
 Pro-einbryo (pro, before; embryo). 
 In phanerogams, the chain of cells 
 (suspensor) formed after fertilization, 
 and from the lower end of which the 
 embryo develops. 
 
 Pro-tha'1-li -uin, pi. prothallia(pro, 
 before ; thallus, a young- shoot). In 
 pteridophytes, the small usually 
 short-lived plant which develops from 
 the spore, and bears the sex-organs. 
 
 Pro-to-ne'-ma, pi. protone'inata 
 (TrpuiTo?, first ; JJjota., that ivhick is sent 
 out). In mosses, the filamentous, 
 growth which is produced by the 
 spores, and from which the leafy 
 moss plant is developed. 
 
 Pro-to'pli-y-ta (TTPUJTOS, the first; 
 <f>vTov, a plant). A primary division 
 of plants, named from the fact that 
 they include the lowest known plants. 
 Pro'-to-phyte\?, the English equivalent 
 
 Pro'-to plasm (7rpo>Tos, first ; 7rAot<r/u.a, 
 that which has been formed). That 
 substance in living cells, of varying 
 consistency, which is the seat of all 
 vital phenomena. 
 
 Pte'r-i-doid (n-Tepis, a fern; elfios, 
 form). Fern like. 
 
 Pter-i-do'pll-y-ta (irrepts, a fern; 
 </>uTOf, a plant). A primary division 
 of plants, named from its principal 
 group, the ferns. Pte-ri' d-o-pJiyte is 
 the English equivalent. 
 
 Py'r-e-noid (irvp^v, kernel; eiSos. 
 form). Minute colorless bodies im- 
 bedded in the chlorophyll structures 
 of some lower plants. 
 
 lla'pli-i-de* (pat/us, a needle; etfios, 
 form). Needle-like plant-crystals. 
 
 Ke-ce'p ta-cle (receptaculum, a recep- 
 tacle). That portion of an axis or 
 pedicel (usually broadened) which 
 forms a common support for a cluster 
 of organs, in most cases sex-organs. 
 
 Ke-ti'c-u-la-ted (reticulatus, net-like). 
 Having a net-like appearance. 
 
GLOSSARY. 
 
 249 
 
 Rha'-chig (pixi?, the backbone}. The 
 axis of a compound leaf, or of a spike. 
 
 Kha'-phe (pa^>^, a stunt). In an anat- 
 ropous ovule, the ridge which con- 
 nects the chala/a with the hilum. 
 
 Khi /oitl (p'i'a. a root ; elfios, form). 
 Root-like ; a name applied to the root- 
 like hairs found in bryophytes and 
 pteridophytes. 
 
 Rhi'-zo-tax-y ip'ia, a root; rafts, ar- 
 rangement). Root-arrangement. 
 
 Roo't stock. A horizontal, more or 
 less thickened, root like stem, either 
 on the ground or underground. 
 
 Sca-la'r-i-form (scalaria, a ladder; 
 forma, form}. A name applied to 
 ducts with pits horizontally elongated 
 and so placed that the intervening 
 thickening ridges appear like the 
 rounds of a ladder. 
 
 Scale (scala, a Jliglit of steps). Any 
 thin scarious body, as a degenerated 
 leaf, or flat trichome. 
 
 Scle-re'ii chy-ma (o-KA^po?, hard: 
 tyxvua, an infusion). A tissue be- 
 longing to the fundamental system 
 and composed of cells that are thick- 
 walled, often excessively so. 
 
 Sen te'l-lum (scutella, a small disk)- 
 The disk-like or shield-like cotyledon 
 of grasses. 
 
 Seed. The fertilized and matured 
 ovule. 
 
 Se'p al (from the modernized word 
 o-eVaAoi', a sepal). A calyx leaf. 
 
 Se'-ta, pi. setae (seta, a bristle). A 
 bristle, or bristle-shaped body ; in 
 mosses, the stalk of the capsule. 
 
 Sheath. A thin enveloping part, as of 
 a filament, leaf, or resin-duct. 
 
 Sieve-cells. Cells belonging to the 
 phloem, and characterized by the pres- 
 ence of circumscribed and perforated 
 panels in the walls ; the panels are 
 sieve-plates, and the perforations 
 sieve-pores. 
 
 So'-rus, pi. sorl (o-topo?, a heap}. In 
 ferns, the groups of sporangia, con- 
 stituting the so-called " fruit-dots ; " 
 in parasitic fungi, well-defined groups 
 
 of spores, breaking through the epi- 
 dermis of the host. 
 
 Spike (spica, an ear of corn). A flower- 
 cluster, having its flowers sessile on 
 an elongated axis. 
 
 Spi'ke-let (diminutive of spike). A 
 secondary spike ; in grasses, the ulti- 
 mate flower-cluster, consisting of one 
 or more flowers subtended by a com- 
 mon pair of glumes. 
 
 Spo-ra'n-gi-um, pi. sporangia 
 (spore ; ayyos, a vessel). The spore- 
 vessel ; applied to ferns and certain 
 lower groups. 
 
 Spore (<r7ropa, seed). Originally used 
 as the analogue of seed in flowerless 
 plants -, now applied to any one-celled 
 or few-celled body which is separated 
 from the parent for the purpose of 
 reproduction, whether sexually or 
 asexually produced ; the different 
 methods of its production are indi- 
 cated by suitable prefixes. 
 
 Spo-ro go'-ni-um, pi. sporogonia 
 (spore ; yoyjj, offspring). The whole 
 structure of the spore-bearing stage 
 of bryophytes. 
 
 Sta'-meil (arr^w, the -warp or thread 
 of cloth). The male organ in phane- 
 rogams. 
 
 Sti'g-ma (o-riy/uia, a spot, or mark). 
 The surface of a pistil without epi- 
 dermis which receives the pollen. 
 
 Stig-ma't-ic. Relating to the stigma, 
 or stigma-like. 
 
 Sto'-ma, pi. sto'mata (orojbta, a 
 mouth). Epidermal structures which 
 serve for facilitating gaseous inter- 
 changes with the external air, often 
 called "breathing-pores." 
 
 Stro'-phi-ole (strophiolum, a small 
 wreath). An appendage at the hilum 
 of certain seeds. 
 
 Style (oriJAos, a pillar}. The usually 
 attenuated portion of the pistil which 
 bears the stigma. 
 
 Sus-pe'n-sor (suspendo, / hang). See 
 Pro-embryo. 
 
 Syn-e'r-gi dae, or Synergides 
 (o-vi'epyeto, / ivork together). The two 
 nucleated bodies which accompany 
 
250 
 
 GLOSSARY. 
 
 the oosphere in the embryo-sac, and 
 together with it form the egg-appara- 
 tus. 
 
 Te's-ta (testa, a shell). The outer 
 seed-coat. 
 
 Tt-ra-dy'n-a-inous (Terpas, four; 
 SuVa/oas, strength}. Said of an andrce- 
 cium in which there are four long and 
 two shorter stamens. 
 
 Tha'1-loid (thallus ; elfios, form). 
 Thallus-like. 
 
 Tha'1-lus (0aAA.6?, a young shoot). 
 The body of lower plants, which ex- 
 hibits no differentiation of stem, leaf, 
 and root. 
 
 The' ca, pi. thecae (0rJKTj, a case). The 
 "anther-cell," that is, the case con- 
 taining pollen ; sometimes used of 
 other spore-cases. 
 
 Tra'cheary tissue. A general name 
 given to the yessels and ducts found 
 in fibro vascular bundles. 
 
 Tra'-che-ides (rpa^vs, rough; elSos, 
 form). Tracheary cells that are closed 
 throughout. 
 
 Tri'-chome (0pt, hair). A general 
 name for a slender outgrowth from 
 the epidermis, usually arising from a 
 single cell. 
 
 Tur-gi'd i ty (turgidus, swollen*). The 
 normal swollen condition of cells 
 which results from the avidity of pro- 
 toplasm for water. 
 
 Vein (vena, a vein). The fibre-vascu- 
 lar bundle of leaves or any flat organ. 
 
 Ve na'-tion (vena, a vein). The mode 
 of vein distribution. 
 
 Xy'-lem (f JA.oi', wood). The wood 
 (inner) portion of the fibre-vascular 
 bundle. 
 
 Zo'-o-spore (Aov, an animal ; spore). 
 A free-moving spore. 
 
 Zy-go-mo'r-phic (vyov, a yoke: 
 Mop<J7, form). Said of a flower which 
 can be bisected by only one plane into 
 similar halves. 
 
 Zy-go'ph-y-ta (vyov, a yoke ; $VTOV, a 
 plant). A primary division of plants, 
 named from their mode of reproduc- 
 tion, the sexual spore being produced 
 by conjugation. Zy'-go-phyte is the 
 English equivalent. 
 
 Zy'-go-spore (fryov, a yoke: spore). 
 The spore of zygophytes, formed by 
 conjugation. 
 
INDEX 
 
 Numbers in light type refer to the laboratory part, those in heavy 
 type to other parts of the book. 
 
 ALTERNATION of generations, 100 
 
 Acliantum, means of recognizing, 
 103; gross anatomy, 105; mi- 
 nute anatomy, in; annotations, 
 124 
 
 Anatropous ovule, 214, 217 
 
 Androecium, 202 
 
 Annual rings, 162 
 
 Annulus, no, 120 
 
 Anther, 178, 189, 203, 226 
 
 Antheridia, 47, 48, 55, 63, 72, 82, 
 88, 93, 122, 128, 168 
 
 Antherozoids, 63, 72, 82, 93, 100, 
 122, 128, 169 
 
 Anthotaxy, 176 
 
 Antipodal cells, 241 
 
 Apical cell, nS 
 
 Apophysis, 89, 96 
 
 Appendages of perithecia, 54, 57 
 
 Archegonia, 75, 77, 82, 88, 94,123, 
 129, 161, 168 
 
 Areolae, 60 
 
 Asci, 54 
 
 Ascospores, 54 
 
 Atrichum, how to recognize, 84; 
 gross anatomy. 86; minute 
 anatomy, 90; annotations, 97; 
 
 discovery of the sexual organs, 
 99; nature of the fruit, 100 
 
 Avena, gross anatomy, 172; mi 
 nute anatomy, i8o;annotations, 
 192; homology of the flower, 193 
 
 Awn, 177 
 
 Axis of inflorescence, 176 
 
 BARK, 136 
 
 Bast parenchyma, 209 
 
 Blade of leaf, 175 
 
 Books of reference, 20 
 
 Bordered pits, 144, 147, 164 
 
 Bracts, 139, 162, 193, 237 
 
 Branches, arrangement of, 133 
 
 Bulliform cells, 195 
 
 Bundle sheath, in, 113, 126, 153. 
 
 155, 181, 184, 206, 219, 229, 
 
 231, 240 
 
 CALLUS-PLATE, 165 
 Calyptra, 86, 89, 97, 101 
 Calyx, 202 
 
 Cambium, 142, 144, 147, 164, 239 
 Camel's-hair brush, how mount- 
 ed, 3 
 Camera lucida, use of. 19 
 
2 5 2 
 
 INDEX. 
 
 Campylotropous seed, 227 
 Canal of archegonia, 77, 94, 123, 
 
 129 
 Capsella, how to recognize, 222; 
 
 gross anatomy, 223; minute 
 
 anatomy, 228; annotations, 236 
 Capsule, 86, 89, 95, 101 
 Carpellary scale, 139, M ^Q. 
 
 163 
 
 Carpels, 163, 202, 204, 213, 217 
 Carpogonium, 55 
 Carpophyll, 163 
 Carpophyta, 48, 55 
 Caryopsis, 179 
 
 Caulicle, 141, 180, 192, 228, 236 
 Cell, 25; division of the, 26 
 Cell-sap, 40 
 Cellulose, 26 
 Cell-wall, 24, 26 
 Chaff of moss, 88; of oats, 179 
 Chalaza, 205 
 Chlor-iodide of zinc, 5 
 Chlorophyll, test for, 23, 29, 31; 
 
 nature of, 25; bands, 36, 40; 
 
 bodies, 24, 77, 119 ; grains, 67, 
 
 77 
 
 Cilia, 26, 47, 73, 83, 94, 100, 123 
 Closed bundle, 195, 209, 220 
 Collateral bundle, 165, 195, 240 
 Columella, 90, 95 
 Concentric bundle, 114, 126 
 Conducting tissue of style, 221, 
 
 241 
 
 Cones, 140, 159 
 Conidia, 44, 45, 50, 53, 56 
 Conidiophores, 45, 46, 53 
 Conjugating filaments, 35; tubes, 
 
 38 
 Connective of anther, 189, 203, 
 
 212 
 Conocephalus, 59, 61 
 
 Continuity of protoplasm, 127 
 
 Cork, 229 
 
 Corolla, 202 
 
 Corpuscula, 161 
 
 Cotyledons, 141, 180, 228, 236 
 
 Cover-glasses, cleaning, 11; kind 
 
 to use, 3; receptacle for, 11 
 Cupules, 60, 62, 68 
 Cuticle, 112, 146, 152, 183 
 Cystopus, where found, 43; gross 
 anatomy, 44; minute anatomy, 
 45; annotations, 48; mode of 
 life, 49; means of distribution, 
 49; nature of its parasitism, 50 
 
 DARK-GREEN scum, 28 
 Definitive nucleus, 241 
 Dermatogen, 182, 206 
 Dichotomous branching, 60, 79 
 Dicotyledons, characters of, 236 
 Dispersion of offspring, 50, 170 
 Drawing, importance of, 16; kinds 
 
 of, 17, 18; suitable materials 
 
 for, 4 
 
 ELATERS, 65, 76, 83 
 
 Embryo, 141, 170, 179. 192, 205, 
 
 215, 228, 235 
 Embryonal vesicle, 241 
 Embryo-sac, 140, 160, 169, 214, 
 
 235, 241 
 
 Empty glume, 176 
 Endogenous origin of roots, 192. 
 
 208, 220 
 Endosperm, 140, 141, 160, 169, 
 
 178, 241 
 Endospore, 121 
 Endothecium, 189, 213, 234 
 Epidermis, 66, 91, 112, 118, 152, 
 
 154, 157, 181, 183, 186, 188, 211, 
 
 230 
 
INDEX. 
 
 253 
 
 .Epiphragm, 89, 96, 101 
 Exogenous growth, 208, 220 
 Exospore, 121 
 Extine> 158, RJO. 213, 234 
 
 FERTILIZATION, mode of contact 
 
 in, 169; in Finns, 170 
 Fertilizing-tube, 48, 49, 51, 169 
 Fibrous tissue, 120 
 Fibro-vascular bundle, 113, 125. 
 
 153, 166, 181, 184, 209, 229, 230 
 Filament of stamen, 178, 203, 212, 
 
 226. 233 
 
 Flowering glume, 177, 193 
 Flower, character of a true, 216; 
 
 in Pinus, 162; nature of, in oats, 
 
 193 
 
 Forceps, 3 
 Frond, 105 
 Funiculus, 205, 214, 227 
 
 GEM.M.E. 60, 62. 70. 80 
 Germination of conidia, 56; of 
 
 moss spores, 102 
 Glume, 176, 177, 188, 193 
 Gluten-containing cells, 191 
 Glycerine, 6, 13 
 Grain of oats, 179, 195 
 Green slime, 22 
 Growing.point, 151, 182, 195, 200, 
 
 208, 219 
 
 Growth rings, 135, 142, 162. 165 
 Guard-cells, 66, 118, 152,166, 183, 
 
 1 86 
 Gyncecium, 202 
 
 HAIRS of thallus, 60, 61, 78; of 
 Cjpule, 69; of fruit, 179 
 
 Haustofia, 46, 49, 53, 56 
 
 Head of liverwort, 63, 64, 81; of 
 moss, 86, 87, 93 
 
 Hermaphrodite flower, 194 
 
 Hygroscopic cells, 176, 187, 195 
 
 Hymenium, 45 
 
 Hyphae, 46 
 
 Hypoderma, 152, 154, 183 
 
 INWSIUM, no 
 
 Instruments for laboratory, 1 
 
 Integument of ovule, 139, 159, 
 
 163, 235 
 
 Intercellular spaces, 127, 185, 209 
 Iniernodes, 105, 174, 199 
 Inline, 158, 170, 190, 213, 234 
 Iodine, 5 
 
 KEEL of carpellary scale, 139, 164 
 
 LAMINA, 87, 92 
 
 Leaf-trace, 91, 99, 219 
 
 Leaves of Marchantia, 61, 68,79; 
 of Atrichum, 87. 92 98; of 
 Adiantum 107, 118; of Pinus, 
 137. 151, 162; of Avena, 175; of 
 Trillium, 220; of Capsella, 225 
 
 Ligule, 175, 193 
 
 Lilac mildew, 52 
 
 Liverwort, 58 
 
 Lodicules, 177, 193 
 
 Lunularia, 59 
 
 MACROSPORES, 168, 241 
 
 Magenta, 5 
 
 Magnifying power of micro- 
 scope, 18 
 
 Maiden-hair fern, 104 
 
 Marchantia, how to recognize. 
 58; gross anatomy, 59; minute 
 anatomy 66; annotations, 77 
 
 Material, care and use of, 15 
 
 Medullary rays, 135, 142, 145, 240 
 
 Meristem, 151, 206, 228 
 
254 
 
 INDEX. 
 
 Mesophyll, 109, 119, 138, 153, 
 155, 166, 175, 187, 210, 232 
 
 Microscope, use of, 6; fine ad- 
 justment, 16; high and low pow- 
 ers, 3; to determine magnifying 
 power, 18 
 
 Microsphaera, how to recognize, 
 52; gross anatomy, 52; minute 
 anatomy, 53; annotations, 55 
 
 Microspores, 168, 240 
 
 Micropyle, 139, 140, 159 
 
 Middle lamella, 112, 127, 144, 207 
 
 Midrib of thallus, 60; of leaf, 87, 
 92, 99 
 
 Moss, 84 
 
 Mounting, 11 
 
 Movements of Oscillaria, 32 
 
 Mycelium, 45, 53 
 
 NAKED ovule in Pinus, 163 
 
 Nectaries, 226 
 
 Needles for dissecting, 2 
 
 Nerves, 176 
 
 Nodes, 105, 174, 192, 199 
 
 Nucellus, 140, 159, 214 
 
 Nucleolus, 24. 38 
 
 Nucleus, 24, 25, 37; of starch, 112 
 
 Nutritive solution, 34 
 
 OATS, 172 
 
 Oogonia, 47, 48 
 
 Oophyta, 48 
 
 Oosphere, 47, 77, 83, 94, 100, 
 
 124, 129, 170, 241 
 Oospore, 44, 48, 49, 235, 242 
 Open bundle, 240 
 Operculum, 89, 96 
 Oscillaria, occurrence of, 28; 
 
 gross and minute anatomy, 29; 
 
 annotations, 31; movements of, 
 
 32 
 
 Ovary, 178, 195. 203, 214. 221, 
 
 234, 238 
 Ovules, 139, 140, 162, 178, 194, 
 
 204, 214, 217, 235 
 
 PALET, 177, 188, 193 
 
 Palisade parenchyma, 187, 210, 
 
 232 
 
 Panicle, 176 
 
 Paraphyses, 72, 75, 82, 88, 93 
 Parenchyma, 67, 70, 113, 142, 
 
 143, 145, 153, 183, 187, 209 
 Parthenogenesis, 51, 55 
 Pedicel of receptacle, 60, 62, 70, 
 
 73, 81; of gemma, 70; of flower. 
 
 223, 237; of conidia, 45; of 
 
 archegonia, 94; of asci, 54; of 
 
 antheridia, 72, 93 
 Peduncle, 139 
 Pencils for drawing, 4 
 Pens for drawing, 4 
 Perianth, 65, 76. 194, 216 
 Periblem, 182, 206 
 Pericambium, 117, 126, 207 
 Perichaetium, 64, 75, 82 
 Peristome, 89, 96 
 Perithecia, 53, 54 
 Petals, 202, 212, 226, 233, 238 
 Petiole, 201 
 
 Phloem, 113, 142, 144, 153, 209 
 Phycocyanine, 29, 31 
 Phyllotaxy, 225 
 Pinnae, 108 
 Pinnules, 107, 108 
 Pistil, 178, 227, 234 
 Pith, 135, 142, 231; for section 
 
 cutting, 10 
 Pits in cell-wall, 112, 127, 144, 
 
 147, 152 
 
 Placentae, 204, 217 
 Plerome, 182, 206 
 
INDEX. 
 
 255 
 
 Plumule, 141, 180, 192 
 
 Pod, 205 
 
 Pollen, 138, 158, 169, 178, 189, 
 
 190, 194, 203, 213, 227, 234 
 Pollen sac, 138, 157, 194 
 Pollen tube, 169, 235, 241 
 Pollination in Pinus, 164 
 Polytrichum 85 
 Pond scum, 33 
 Potassic chlorate, 6; hydrate, 5, 
 
 13 
 
 Primary meristem, 151, 206 
 Primordial utricle, 40 
 Pro embryo, 235, 242 
 Prothallia, 104, in, 121, 128, 
 
 168, 194, 241 
 Protococcus, distribution of, 22; 
 
 gross and minute anatomy, 23; 
 
 annotations, 25 
 Protonema, 86, 90, 102 
 Protoplasm, test for, 24, 25; in 
 
 the cell, 40; in pollen, 158 
 Pteridoid stage, 128 
 Punctum vegetationis, 219 
 Pyrenoid, 37, 40 
 
 RADIAL bundle, 117, 126, 195, 218 
 
 Radish flowers, 43 
 
 Raphides, 201, 233 
 
 Razor, kind to use, 2; care of, 9 
 
 Reagents, 4; use of , 13 
 
 Receptacle, 60, 64, 71, 74, 87, 
 
 202, 226 
 
 Reference books, 19 
 Resin-ducts, 135, 143, 145, 148 
 
 153, 155, 167 
 
 Resting spores, 42, 49, 56 
 Rhachis of leaf, 107; of spikelet, 
 
 177 
 
 Rhaphe, 205 
 Rhizoids, 61, 79, 86, 90, in, i?2 
 
 Rhizome, 105 
 
 Rhizotaxy, 223 
 
 Roots,- 79, 105, 116, 124, 173, 
 
 219, 238 
 Root cap, 107, 118, 124, 174, 182, 
 
 205, 238 
 
 Root-hairs, 97, 107, 118, 174, 206 
 Root-sheath, 180, 192 
 Root-stock, 198, 199, 207, 218 
 
 SCALARIFORM VCSSels, 133, JI4, 
 
 "7 
 
 Scale leaves of Atrichum, 87; of 
 Pinus, 132, 137, 146, 149, lefc; 
 of Trillium, 200, 201, 218 
 
 Scales (trichomes) on rhizome, 
 105, 107. 116; on thallus, 60, 
 62, 79 
 
 Sclerenchyma, in, 115 
 
 Scotch pine, 130 
 
 Scutellum, 180, 192 
 
 Section cutting, 8 
 
 Seed, 141, 170. 205, 215, 227, 236 
 
 Selaginella, 168 
 
 Sepals, 202, 2ii, 226, 233 
 
 Seta, 86, 89, 95, 100 
 
 Sexuality, simplest form of, 42; 
 significance of, 51 
 
 Sexual process, 41 
 
 Sheath of filament, 30, 31, 36, 39; 
 of leaf, 175, 188; of resin duct, 
 143; of root, 1 80. 192; of root- 
 stock, 208, 220; of bundle see 
 Bundle sheath 
 
 Shepherd's-purse, 222 
 
 Sieve cells, 113, 115, 144, 148, 
 165; plates, 115, 126, 145, 165; 
 tissue, 207, 209 
 
 Sori, 44, no 
 
 Sperm-cell, 122 
 
 Spike, 139 
 
2 5 6 
 
 INDEX. 
 
 Spikelet, 176 
 
 Spiral vessels, 143, 225 
 
 Spirogyra, occurrence of 33; to 
 grow, 34; gross anatomy, 34; 
 minute anatomy, 35; annota- 
 tions, 39 
 
 Spongy parenchyma, 210, 221, 
 232 
 
 Sporangia, no, 120 
 
 Sporogonia, 64, 76, 83, 86, no, 
 120 
 
 Staining, 13 
 
 Stamens, 132, 138, 157, 162, 178, 
 194, 202, 212, 226, 233, 238 
 
 Starch, 37, 40, 112, 158 
 
 Stigmas, 178, 190, 194, 204, 217, 
 234 
 
 Stigmatic cells, 77, 83, 94; sur- 
 faces, 213 
 
 Stomata, 61, 66, 68, 71, 78, 101, 
 119, 127, 138, 152, 188 
 
 Strophiole, 205, 215 
 
 Styles, 178, 190, 204, 217 
 
 Subterranean stem, 199 
 
 Sulphuric acid, 6, 13 
 
 Supplementary guard-cells, 66 
 
 Suspensor, 242 
 
 Synergidse, 241 
 
 TAP root, 237 
 
 Teeth of the peristome, 97, 101 
 
 Testa, 205, 215, 236 
 
 Tetradynamous stamens, 237 
 Thalloid stem, 77, 128 
 Thallus, 59, 66, 77 
 Thecse of anther, 189, 203, 2J2, 
 
 234 
 
 Tillering point, 173 
 Tracheides, 143, 147, 164, 167, 182 
 Transfusion tissue, 167 
 Trichomes, 61, 66, 75, 105^, 120, 
 
 122, 125, 173, 191 
 Trillium, description of, 197; 
 
 gross anatomy, 198; minute 
 
 anatomy, 205; annotations, 215 
 Turgidity of cells, 30, 32, 38 
 
 VEINS, 109, 201, 2ii 
 Venation, 109, 218 
 Vesicle of antherozoid, 73, 83, 94, 
 123 
 
 WHITE rust, 43 
 
 Wings of thallus, 60; of pollen, 
 
 158 
 Wood, 135, 142, 164; cells, 143; 
 
 parenchyma, 209 
 
 XYLEM, 113, 142, 143, 147, 153, 
 209 
 
 ZOOSPORES, 26, 47, 50 
 Zygophyta, 48 
 Zygospores, 35, 39, 42 
 
THE AMERICAN SCIENCE SERIES. 
 
 The principal objects of the series are to supply the lack in 
 some subjects very great of authoritative books whose princi- 
 ples are, so far as practicable, illustrated by familiar American 
 facts, and also to supply the other lack that the advance of Sci- 
 ence perennially creates, of text-books which at least do not 
 contradict the latest generalizations. The scheme systemati- 
 cally outlines the field of Science, as the term is usually em- 
 ployed with reference to general education, and includes 
 ADVANCED COURSES for maturer college students, BRIEFER 
 Cor USES for beginners in school or college, and ELEMENTARY 
 COURSES for the youngest classes. The Briefer Courses are not 
 mere abridgments of the larger works, but, with perhaps a 
 single exception, are much less technical in style and more 
 elementary in method. While somewhat narrower in range 
 of topics, they give equal emphasis to controlling principles. 
 The following books in this series are already published: 
 
 THE HUMAN BODY. BY H. NEWELL MARTIN, Professor in 
 
 the Johns Hopkins University. 
 Advanced Course. Large I2mo. Pp. 655. $2 75. 
 
 Designed to impart the kind and amount of knowledge every 
 educated person should possess of the structure and activities 
 and the conditions of healthy working of the human body. 
 While intelligible to the general reader, it is accurate and suffi- 
 ciently minute in details to meet the requirements of students 
 who are not making human anatomy and physiology subjects of 
 special advanced study. The regular editions of the book contain 
 an appendix on Reproduction and Development. Copies without 
 tht< will be sent when specially ordered. 
 
 From the CHICAGO TRIBUNE: " The reader who follows him through 
 to the end of the book will be better informed on the subject of 
 ir.odern physiology in its general features than most of the medical 
 practitioners who rest on the knowledge gained in comparatively an- 
 tiquated text-books, and will, if possessed of average good judgment 
 and powers of discrimination, not be in any way confused by state- 
 ments of dubious questions or conflicting views." 
 
2 THE AMERICAN SCIENCE SERIES. 
 
 THE HUMAN BODY Continued. 
 Briefer Course. 12010. Pp. 364. $1.50. 
 
 Aims to make the study of this branch of Natural Science a 
 source of discipline to the observing and reasoning faculties, 
 and not merely to present a set of facts, useful to know, which 
 the pupil is to learn by heart, like the multiplication-table. 
 With this in view, the author attempts to exhibit, so far as is 
 practicable in an elementary treatise, the ascertained facts of 
 Physiology as illustrations of, or deductions from, the two car- 
 dinal principles by which it, as a department of modern science, 
 is controlled, namely, the doctrine of the "Conservation of 
 Energy" and that of the " Physiological Division of Labor." To 
 the same end he also gives simple, practical directions to assist 
 the teacher in demonstrating to the class the fundamental facts 
 of the science. The book includes a chapter on the action upon 
 the body of stimulants and narcoiics. 
 
 From HENRY SEWALL, Professor of Physiology, University of Michi- 
 gan : " The number of poor books meant to serve the purpose of 
 text-books of physiology for schools is so great that it is well to 
 define clearly the needs of such a work : I. That it shall contain ac- 
 curate statements of fact. 2. That its facts shall not be too numer- 
 ous, but chosen so that the important truths are recognized in their 
 true relation. 3. That the language shall be so lucid as to give no 
 excuse for misunderstanding. 4. That the value of the study as a 
 discipline to the reasoning faculties shall be continually kept in view. 
 I know of no elementary text-book which is the superior, if the 
 equal, of Prof. Martin's, as judged by these conditions." 
 
 Elementary Course. I2mo. Pp. 261. 90 cts. 
 
 A very earnest attempt to present the subject so that children 
 may easily understand it, and, whenever possible, to start with 
 familiar facts and gradually to lead up to less obvious ones. 
 The action on the body of stimulants and narcotics is fully treated. 
 
 From W. S. PERRY, Superintendent of Schools, Ann Arbor, Mich. : 
 " I find in it the same accuracy of statement and scholarly strength 
 that characterize both the larger editions. The large relative space 
 given to hygiene is fully in accord with the latest educational opinion 
 and practice ; while the amount of anatomy and physiology comprised 
 in the compact treatment of these divisions is quite enough for the 
 most practical knowledge of the subject. The handling of alcohol 
 and narcotics is, in my opinion, especially good. The most admira- 
 ble feature of the book is its fine adaptation to the capacity of younger 
 pupils. The diction is simple and pure, the style clear and direct, and 
 the manner of presentation bright and attractive." 
 
THE AMERICAN SCIENCE SERIES. 3 
 
 ASTRONOMY. BY SIMON NEWCOMB, Professor in the Johns 
 Hopkins University, and EDWARD S. HOLDEN, Director of 
 the Lick Observatory. 
 
 Advanced Course. Large 12 mo. Pp. 512. $2.50. 
 
 To facilitate its use by students of different grades, the sub- 
 ject-matter is divided into two classes, distinguished by the size 
 of the type. The portions in large type form a complete course 
 for the use of those who desire only such a general knowledge 
 of the subject as can be acquired without the application of ad- 
 vanced mathematics. The portions in small type comprise ad- 
 ditions for the use of those students who either desire a more 
 detailed and precise knowledge of the subject, or who intend to 
 make astronomy a special study. 
 
 From C. A. YOUNG, Professor in Princeton College: " I conclude 
 that it is decidedly superior to anything else in the market on the 
 same subject and designed for the same purpose." 
 
 Briefer Course. I2mo. Pp. 352. $1.40. 
 
 Aims to furnish a tolerably complete outline of the as- 
 tronomy of to-day, in as elementary a shape as will yield satis- 
 factory returns for the learner's time and labor. It has been 
 abridged from the larger work, not by compressing the same 
 matter into less space, but by omitting the details of practical 
 astronomy, thus giving to the descriptive portions a greater 
 relative prominence. 
 
 From THE CRITIC: "The book is in refreshing contrast to the 
 productions of the professional schoolbook-makers, who, having only 
 a superficial knowledge of the matter in hand, gather their material, 
 without sense or discrimination, from all sorts of authorities, and 
 present as the result an indigesta moles, a mass of crudities, not un- 
 mixed with errors. The student of this book may feel secure as to 
 the correctness of whatever he finds in it Facts appear as facts, and 
 theories and speculations stand for what they are, and are worth." 
 
 From W. B. GRAVES, Master Scientific Department of Phillips 
 Academy: " I have used the Briefer Course of Astronomy during the 
 past year. It is up to the times, the points are put in a way to inter- 
 est the student, and the size of the book makes it easy to go over the 
 subject in the time allotted by our schedule." 
 
 From HENRY LEFAVOUR, late Teacher of Astronomy, Williston Semi- 
 nary : "The impression which I formed upon first examination, that 
 it was in very many respects the best elementary text book on the 
 subject, has been confirmed by my experience with it in the class- 
 room." 
 
4 THE AMERICAN SCIENCE SERIES. 
 
 ZOOLOGY. By A. S. PACKARD, Professor in Brown Univer- 
 sity. 
 Advanced Course. Large I2mo. Pp. 719. $3.00. 
 
 Designed to be used either in the recitation-room or in the 
 laboratory. It will serve as a guide to the student who, with a 
 desire to get at first-hand a general knowledge of the structure 
 of leading types of life, examines living animals, watches their 
 movements and habits, and finally dissects them. He is pre- 
 sented first with the facts, and led to a thorough knowledge 
 of a few typical forms, then taught to compare these with 
 others, and finally led to the principles or inductions growing 
 out of the facts. 
 
 From A. E. VERRILL, Professor of Zoology in Yale College : ' ' The 
 general treatment of the subject is good, and the descriptions of 
 structure and the definitions of groups are, for the most part, clear, 
 concise, and not so much overburdened by technical terms as in sev- 
 eral other manuals of structural zoology now in use." 
 
 Briefer Course. i2mo. Pp. 334. $1.40. 
 
 The distinctive characteristic of this book is its use of the 
 object method. The author would have the pupils first examine 
 and roughly dissect a fish, in order to attain some notion of 
 vertebrate structure as a basis of comparison. Beginning then 
 with the lowest forms, he leads the pupil through the whole 
 animal kingdom until man is reached. As each of its great 
 divisions comes under observation, he gives detailed instruc- 
 tions for dissecting some one animal as a type of the class, and 
 bases the study of other forms on the knowledge thus obtained. 
 
 From HERBERT OSBORN, Professor of Zoology, Iowa Agricultural 
 College : " I can gladly recommend it to any one desiring a work of 
 such character. While I strongly insist that students should study 
 animals from the animals themselves, a point strongly urged by 
 Prof. Packard in his preface, I also recognize the necessity of a 
 reliable text-book as a guide. As such a guide, and covering the 
 ground it does, I know of nothing better than Packard's." 
 
 From D. M. FISK, Professor of Natural History, Hillsdale College : 
 " The 'Briefer Courses ' of Packard and Martin have been adopted, 
 and for these reasons : I. They are brief ; the lessened mechanical 
 labor of mastering a text leaves time for more observation and for 
 comparison of authorities. 2. They are clear ; the work of cutting 
 away needless nomenclature has been done with skill. 3. They are 
 authoritative ; serious students can have confidence in even brief and 
 dogmatic statements, knowing they come from a master, and not from 
 a mere compiler. 4. Thev are fresh ; fossils are good in their places, 
 but a fossil text-book in science is a fraud on youth." 
 
THE AMERICAN SCIENCE SERIES. 5 
 
 ZOOLOGY Continued. 
 Elementary Course. (In press.} 
 
 In general method this book is the same with those just de- 
 scribed, but, being meant for quite young pupils, it gives more 
 attention to the higher organisms, and to such particulars as 
 can be studied with the naked eye. In everything the aim has 
 been to make clear the cardinal principles of animal life, rather 
 than to fill the pupil's mind with a mass of what may appear to 
 him unrelated facts. 
 
 BOTANY. By CHARLES E. BESSEY, Professor in the Univer- 
 sity of Nebraska. 
 Advanced Course. Large 12 mo. Pp. 611. $275. 
 
 Aims to lead the student to obtain at first-hand his knowl- 
 edge of the anatomy and physiology of plants. Accordingly, 
 the presentation of matter is such as to fit the book for con- 
 stant use in the laboratory, the text supplying the outline sketch 
 which the student is to fill in by the aid of scalpel and micro- 
 scope. 
 
 From J. C. ARTHUR, Editor of The Botanical Gazette: "The first 
 botanical text-book issued in America which treats the most important 
 departments of the science with anything like due consideration. 
 This is especially true in reference to the physiology and histology of 
 plants, and also to special morphology. Structural Botany and clas- 
 sification have up to the present time monopolized the field, greatly 
 retarding the diffusion of a more complete knowledge of the science." 
 
 Briefer Course. I2mo. Pp.292. $1.35. 
 
 A guide to beginners. Its principles are, that the true aim of 
 botanical study is not so much to seek the family and proper 
 names of specimens as to ascertain the laws of plant structure 
 and plant life; that this can be done only by examining and 
 dissecting the plants themselves ; and that it is best to confine 
 the attention to a few leading types, and to take up first the 
 simpler and more easily understood forms, and afterwards those 
 whose structure and functions are more complex. The latest 
 editions of the work contain a chapter on the Gross Anatomy 
 of Flowering Plants. 
 
 From J. T. ROTHROCK, Professor in the University of Pennsylva- 
 nia : " There is nothing superficial in it, nothing needless introduced, 
 nothing essential left out. The language is lucid ; and, as the crown- 
 ing merit of the book, the author has introduced throughout the vol- 
 ume ' Practical Studies,' which direct the student in his effort to see 
 for himself all that the text -book teaches." 
 
O THE AMERICAN SCIENCE SERIES. 
 
 CHEMISTRY. By IRA REMSEN, Professor in the Johns Hop- 
 kins University. 
 Briefer Course. I2mo. Pp. 387. $1.40. 
 
 An introduction to the study of chemistry, following the 
 inductive method. To avoid overburdening the student's mind, 
 the author has presented a smaller number of facts than is 
 usual in elementary courses in chemistry, but he has at the same 
 time taken pains to select for treatment such substances and 
 such phenomena as seem best suited to give an insight into the 
 nature of chemical action. In other words, he has aimed to 
 make the book scientific, to lay stress upon the relations which 
 exist between the phenomena considered, and not to present 
 merely a mass of apparently disconnected facts. Another 
 feature of the work is that principles and laws are treated be- 
 fore the theories which are proposed to account for them. 
 
 The other books arranged for in this series are as follows : 
 
 PHYSICS. By ARTHUR WRIGHT, Professor in Yale College. 
 {In preparation.} 
 
 CEOLOCY. By RAPHAEL PUMPELLY, late Professor in Har- 
 vard University. (In preparation.) 
 
 PSYCHOLOGY. By WILLIAM JAMES, Professor in Harvard 
 University. (In preparation} 
 
 GOVERNMENT. By EDWIN L. GODKIN, Editor of the Nation, 
 (In preparation} 
 
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 Book Slip-10m-8,'58(5916s4)458 
 
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