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 CONCERNING SOILS, GERMS 
 AND WORMS. 
 
 BY 
 Dr. PERSIFOR FRAZER. 
 
 Reprinted from the Journal of the Franklin Institute, 
 April, 1904. 
 
 PHILADELPHIA 
 
 1 
 
 1904. 
 
Reprinted from the Journal of the Franklin Institute, April, 1904. 
 
 CHEMICAL SECTION. 
 
 Stated Meeting, held March ij, iqoj. 
 
 Concerning Soils, Germs and Worms.* 
 
 By Dr. Persifor Frazer. 
 
 In Part III of the Report of the Geology of New Jersey, 
 of 1868, under the head of "Economic Geology," the 
 Director, Prof. Geo. H. Cook, says : " In the detailed geology 
 and under the proper heads, will be found chemical analyses 
 of gneiss, limestone, slate, shale, trap rock, clay, green sand, 
 etc. The soils are mostly derived from these ; sometimes 
 from one, and sometimes from a mixture of two or more of 
 them. And this geological classification is the best that 
 can be made. A more common classification is into sandy, 
 loamy and clayey soils. The latter, however, is not capable 
 of general use. The meaning of the terms always depends 
 on the experience of the person who uses them. What in one 
 part of the State is called a clayey soil, in another part is 
 called a loamy soil, and in still other places it would be 
 called sandy," etc., etc. This statement will furnish an 
 appropriate introduction to the observations on soils which 
 are here proposed, since it shows how vague is the average 
 conception of the character of that storehouse whence we 
 draw our life. But the farmer's division into sandy, loamy, 
 and clayey is not more crude than was that of the aver- 
 age geologist. To him soils were but the comminuted 
 rocks of the earth's crust mixed with more or less adven- 
 titious organic matter, and moistened by the rain, the dew, 
 and the capillary flow of the ground waters. Professor 
 Cook, as he says, " to show how light or sandy a soil will 
 produce vegetation," instances in the same chapter the fol- 
 lowing analysis of beach sand from Old Beach, Atlantic City : 
 
 * Substance of a lecture delivered before the Pennsylvania Horticultural 
 Society, Tuesday, April 18, 1899, by Dr - Persifor Frazer, Professor of Horti- 
 cultural Chemistry, Penna. Hort. Soc. Subsequently revised to January I, 
 1904, and in part rewritten. 
 
2 
 
 Silicic acid and quartz 95'44 
 
 Alumina 1 JTO 
 
 Peroxide of iron i 
 
 Lime 0*45 
 
 Magnesia o'22 
 
 Water 0*30 
 
 Total 99'4i 
 
 In the report of the geological survey of New Jersey for 
 1879, glass sand and sandy clays are noted as producing 
 oak-land and pine-land soils. 
 
 How very different is the idea of a soil in the minds of 
 the agricultural chemists of the present day may be judged 
 by Wiley's definition (" Principles and Practice of Agricul- 
 tural Analysis." Chemical Pub. Co., Easton, Pa., 1894): 
 " The term soil, in its broadest sense, is used to designate 
 that portion of the surface of the earth which has resulted 
 from the disintegration of rocks and the decay of plants 
 and animals, and which is suited, under proper conditions 
 of moisture and temperature, to the growth of plants. It 
 consists, therefore, chiefly of mineral substances, together 
 with some products of organic life, and of certain living 
 organisms, whose activity may influence vegetable growth 
 either favorably or otherwise. The soil holds various quan- 
 tities of gaseous matter and of water, which are important 
 factors in its functions." Yet it is possible to make plants 
 grow without the intervention of any soil in the sense of 
 the last definition (Storer, "Agriculture in Some of Its Rela- 
 tions with Chemistry " ); for not only does the mistletoe grow 
 in the air, but hyacinths, cuttings of rose bushes, trade scantia, 
 and Indian corn, or almost any of the ordinary grains, may 
 be made to grow and bear seeds in glasses of water, provided 
 the latter contain some ash-producing material and some 
 nitrates, which are ordinarily derived from the soil. How- 
 ever small the amount, some potash, lime, magnesia, iron, 
 phosphoric, sulphuric and nitric acid (or, in the place of the 
 last, ammonia) must be present in order to develop the 
 plants of the higher orders (id. I). 
 
 Soil is necessary as a prop for the plant in nature, as well 
 as a sponge from which to extract the food which is to sus- 
 
tain it ; and for certain plants, such as tubers, the light, 
 easily-displaced covering of pure silica sand, when once well 
 manured, produces more perfectly formed plants than the 
 less yielding natural mold. 
 
 The passage of water and its saline constituents through 
 a plant, and the evaporation of the former (or, more prop- 
 erly, its exhalation, since the process is connected with the 
 life of the plant and may take place, unlike ordinary evapo- 
 ration, when the surrounding atmosphere is saturated with 
 moisture), results in an enormous circulation, estimated by 
 Watson at 30 hogsheads of water on every acre of grass land 
 per day. About 300 parts, by weight, of water pass through 
 a plant to one part fixed and assimilated in its tissues. 
 
 Ordinary soils contain large quantities of nitrogen ; in 
 fact, by a series of experiments on Scotch soils and manures 
 made by Anderson, the average proportion of organic matter 
 in the soils was 7*02, and of nitrogen in this organic matter 
 0*206 ; or a relative proportion of nitrogen to organic matter 
 in the natural soil of somewhere near 1:35; whereas in the 
 manures applied to the eight farms from which these various 
 soils were taken, the average proportion of organic matter 
 was i3'94, and of nitrogen 0'382. The proportion of the 
 nitrogen to the organic matter in the manures was as 
 1 : 36*49. Consequently, the relative proportion of this 
 invaluable plant food element was higher in the natural soil 
 than in the manure laid on to enrich it.* Professor Storer con- 
 
 *It is interesting in this connection to note the " fertilizing ingredients" 
 and their cost, enumerated by Mr. MacFarlane in his admirable report on 
 "Fertilizers." The quantity of each ingredient in a given fertiliztr must, 
 according to Dominion law, be stated by the dealer. (Published by the 
 Inland Revenue Department of Canada, Bulletin 86, Ottawa, 1903. ) 
 Nitrogen in salts of ammonia or nitrates as well as in com- 
 pound fertilizers $0 13 
 
 Organic nitrogen in ground bone, fish, blood or tankage ... 12 
 
 Phosphoric acid — soluble in water 6 
 
 " " " 1 percent, citric acid 5^ 
 
 " insoluble in Thomas' phosphate powder . . 3^ 
 ground rock phosphate and 
 
 fertilizers generally 1% 
 
 Potash contained in wood ashes 6 
 
 " from high-grade salts 5% 
 
siders the utilization of these natural and almost inexhausti- 
 ble supplies of nitrogen among the most important of the 
 problems of to-day, and adds that from remote time the 
 improvement of the soil-nitrogen has been deemed, by wise 
 cultivators, more advantageous than employing fertilizers, 
 or keeping additional cattle to produce more manure. These 
 stores of nitrogen are found in arable loam, leaf mold, peat, 
 swamp and marsh mud, etc., and here is where an agent 
 often neglected renders valuable service, as will be seen 
 further on. 
 
 The effect of " symbiosis," as Storer calls it, or blended 
 life of various kinds, is well illustrated by the little knobs 
 and warts on the roots of clover and leguminous plants. 
 The most generally received explanation of this phenome- 
 non now is that bacteria enter the roots from the soil, and 
 form colonies within the roots, thus giving rise, by the 
 mutual growth of bacteria and plant-cells, to those excres- 
 cences. The lower organisms thrive on the juices of the 
 plant, and in turn render some service in supplying these 
 roots with nitrogen. Hellriegel has shown that nitrogen 
 from the air is stored up for the benefit of such plants, even 
 when the latter are grown in sand free from organic or 
 nitrogenous matter. Nodules form upon the roots at the 
 time that nitrogen is being taken from the air; but material 
 akin to the ash-residue of the normal plant must be strewn 
 with the sand. When growth ceased, in such experiments, 
 occasionally germs from the air fell upon the sand and 
 started the growth anew ; but on supplying water, which 
 had been in contact with garden loam and was charged with 
 bacteria, the full and healthy growth was recommenced, 
 and the plants assumed their normal dark-green color. The 
 plants feed upon the substance of the bacteria after the 
 latter have died. 
 
 These plants, which get nitrogen from the bacteria, charge 
 the soil with nitrogen to the benefit of succeeding crops of 
 other plants ; and this is the modern explanation of the 
 utility of rotation in crops, which has been recognized prob- 
 ably ever since husbandry began. A continuous succession 
 of peas, for example, not only gives rise to nematode 
 
5 
 
 worms, instead of bacteria nodules on the pea roots, but 
 these worms are transferred to the next crop which is put 
 in, and impair or ruin it. 
 
 Great lichens, such as reindeer moss, or Iceland moss, 
 grow freely on bare rocks and sterile soils. Fungoid growths 
 are noticed, even covering in a few days surfaces of iron. 
 These fungi produce large quantities of nitrogenous organic 
 matter. 
 
 Berthelot showed that certain nitro-organisms living in 
 soil feed on the nitrogen of the air, and produce nitrogen 
 compounds, at first insoluble in water, but later converted 
 into soluble nitrates, to the amount of 75 to 100 pounds per 
 acre per annum. 
 
 But the fixation of nitrogen by nitro-organisms in the 
 soil is less important than that by bacteria on the roots of 
 leguminous plants. 
 
 The general conclusions as to nitrogen and micro- 
 organisms in their relations to plants, reached through the 
 work of Atwater, Wagner, Heiden, Hellriegel and Wood 
 (of the Storrs Agricultural School in Connecticut), may be 
 thus summarized : 
 
 Pease, alfalfa, serradella, lupine, probably clover, and in 
 general all leguminous plants acquire large quantities of 
 nitrogen from the free nitrogen of the air during growth. 
 
 It is clear that there is a connection between the root 
 tubercles and this acquisition of nitrogen, but what the con- 
 nection is remains to be discovered. 
 
 Cereals which have been experimented with have not 
 shown this power of taking nitrogen, nor had they such 
 tubercles as are found on the roots of legumes. 
 
 In the experiments undertaken soil infusions did not seem 
 necessary for the production of root tubercles. It is con- 
 sidered probable that the micro-organisms or spores were 
 floating in the air and thence found their way to the pots in 
 which the plants were growing. 
 
 As a rule in the experiments, the greater the abundance 
 of root tubercles, the larger and more vigorous the plants, 
 and the greater the gain of nitrogen from the air. 
 
 Where loss of nitrogen occurred there were no root 
 tubercles. It was largest with oat plants and largest where 
 
they had most nitrogen at their disposal in the form of 
 nitrates. The gain of nitrogen in legumes helps explain 
 why they act as renovating crops, and the loss in the case 
 of oats suggests why they should be an exhausting crop. 
 
 (MacFarlane, Bulletin 86. Canadian Report I. R. D.) 
 
 On barren ledges of rocks the frost and other causes 
 produce disintegration, and the spores of fungi resting on 
 this talus produce nitrogenous matters from the air. The 
 soil is then ready for the next step, which is the making of 
 mold. 
 
 Humus, according to Storer, is the organic portion of all 
 the earth-like products which results from the decay of 
 vegetable or animal matters. In temperate climates the 
 tender parts of vegetable matter are converted by the oxy- 
 gen present into carbon dioxide and water (through micro- 
 organisms chiefly), and the residue is humus, which resists 
 further decay. 
 
 The acids of various constitution, together known as 
 humic acid, though not very soluble in water, are chemic- 
 ally active. 
 
 Agricultural plants, in general, cannot feed directly upon 
 humus, but, through the micro-organisms which feed on it, 
 are supplied with nitrogen. 
 
 Three ferments in all are needed : one to set free am- 
 monia; one to produce nitrites from it; and one to produce 
 nitrates from nitrites. Nitrification is most active in hot 
 summer weather. No nitrates are produced by putrefying 
 processes. On the contrary, nitrates, if present, are con- 
 verted into ammonia. 
 
 In an experiment made by Leone with nitrates and hen- 
 dung in loam, placed in a box so that air could freely pass 
 between the particles, first nitrates were partially reduced 
 to nitrites. In a fortnight both nitrates and nitrites disap- 
 peared, and only ammonia was detected. In little over a 
 month, nitrates again began to appear, and in three months 
 there were only nitrates. Lorgna defines nitrification as the 
 last term of putrefaction. 
 
 The above experiment shows how easily an injudicious 
 treatment of a valuable manure may entirely destroy its 
 efficiency. A few words on the value of farm manure 
 
and the best methods of securing, preserving, increasing its 
 efficacy, and applying it, seem here appropriate. Hell- 
 riegel, in 1897, proposed a simple plan easily applicable 
 everywhere and every year, by means of which a practical 
 agriculturist may see differences between adjacent crops 
 treated differently, and thus decide what should be the 
 substance applied to the soil to insure the best harvest. It 
 is to pass over a few square rods of the field, at various 
 places properly selected, without applying dung or fertilizer. 
 In accordance with this principle other plots of like dimen- 
 sions may be treated respectively with lime, marl, dung, or 
 fertilizers. The heights and densities of the resulting crops, 
 the fulness of the ears and the development of the grains, 
 etc., may easily be compared, and a correct conclusion 
 drawn as to what is best for that particular soil. 
 
 J. Koenig, in his prize essay, " How Can the Farmer Pre- 
 serve and Increase the Stock of Nitrogen on His Property?" 
 (Berlin, 1887), gives the results of his investigations and 
 experience as follows : 
 
 (1) In the decomposition of nitrogenous substances of 
 every nature a loss of free nitrogen, more or less consider- 
 able, takes place. 
 
 (2) This loss is the greater the more the atmosphere has 
 access to the decomposing mass. 
 
 (3) Too much moisture is as hurtful as too little. Stable 
 manure requires such a degree of humidity as permits its 
 components to lie close together. 
 
 (4) The addition of substances which fix ammonia (such 
 as gypsum, kainite, and kieserite) prevents or reduces the loss 
 of nitrogen. These substances are, however, of little or no value 
 if care be not taken at the same time to prevent as much as possi- 
 ble the access of air. 
 
 In storing stable manure, it should be kept in a water- 
 tight receptacle, roofed in, and it is desirable that it be 
 trodden down by the farm animals. It is perfectly clear 
 that the use of gypsum or ordinary ground land plaster pre- 
 vents any loss of nitrogen in the stable, and, according to 
 Holdefieiss, Vogel, and others, the same substance, or gyp- 
 sum produced in the manufacture of the acid phosphate, 
 prevents the loss of ammonia from the liquid part of the 
 
manure. Another suggestion by Dr. C. A. Goessmann, 
 Chemist for the Massachusetts Agricultural College (Bulle- 
 tin 45, March, 1897), is that there should be added to the 
 manurial refuse materials of the farm such single manurial 
 substances as will enrich the former in the directions desir- 
 able for any particular crop. 
 
 (Canadian Inland Revenue Department Bulletin, No. 86, 
 before cited.) 
 
 The substance of the following notes on bacteria is 
 taken from an interesting lecture entitled " The Analysis 
 of Water, Chemical, Microscopical and Bacteriological," 
 before the Lowell Institute, Boston, December 5, 1889, 
 by Dr. Thomas M. Drown, then Professor of Analytical 
 Chemistry in the Massachusetts Institute of Technology, 
 now President of Lehigh University, Pennsylvania. In 
 speaking of the bacteria found in the sanitary analysis of 
 potable waters, he says : The bacteria belong to the lowest 
 form of life ; a simple cell, with wall and contents, capable 
 of self-nourishment and reproduction. Until within a few 
 years their presence was unknown and unsuspected, so 
 minute are they, and yet their importance in the economy 
 of nature is such that higher life would come to an end if 
 their activities were to cease. It is unfortunate that these 
 ever-present, humble, useful organisms should be associated 
 in our minds mainly with evil purpose and effect. True, 
 there are malignant bacteria, to which we cannot assign 
 any beneficial role in nature ; but so there are poisonous 
 fruits. 
 
 The bacteria, or germs, as they are also called, have many 
 shapes ; the ball or egg-like forms include the genera micro- 
 coccus and streptococcus; the rod-like forms, the genus 
 bacillus ; and spiral forms, the genus spirillum. A special 
 form of bacteria we have all become familiar with in name 
 — the cholera germ, called by Koch the comma bacillus. 
 
 The function of the green plant is to make organic ma- 
 terial out of the inorganic. Trees, grass, and vegetables 
 live entirely on the carbonic acid of the air and the water 
 and mineral matters in the soil. Animals cannot do this, 
 but require either vegetable or animal food. In utilizing 
 this food, the animals do not reconvert it all into mineral 
 
matter again. The nitrogen in the proteid, or albuminoid 
 matter which they consume, is not excreted in the oxidized 
 form of nitrates, but as urea, a compound related to am- 
 monia. Then the bacteria step in, find food for their sup- 
 port in the waste which has no more value for animal life, 
 and complete its conversion into mineral matter that it may 
 again serve as food for plants. 
 
 The method employed to determine the numbers of bac- 
 teria is based on the principle that by stimulating their 
 growth and making them increase enormously within a 
 small space, in which they cannot move, the aggregations of 
 the newly developed bacteria will be so large that they can 
 be seen by the naked eye. This ingenious suggestion was 
 carried out by the famous bacteriologist, Koch, in this way: 
 A small quantity, usually i cubic centimeter, of the water 
 (that is, about one-fifth of a teaspoonful) is mixed thor- 
 oughly with, say, ten times its amount of a sterilized solu- 
 tion of gelatine, which contains extract of beef, peptone, 
 etc., to make it highly nutrient, and the mixture is poured, 
 while warm, upon a glass plate, so that it forms a thin layer 
 when solidified. This is set aside for a few days in a warm 
 room under a cover, and protected from the germs in the 
 air. If bacteria are present in the water they will grow 
 with great rapidity under these conditions, each bacterium 
 forming a colony, as it is termed, of thousands or millions 
 of bacteria. Then we can see and count them. It is as- 
 sumed that each colony arose from a single bacterium in 
 the water ; hence, by counting the number of colonies on a 
 plate, we arrive at a determination of the number of bac- 
 teria in the cubic centimeter of water used. 
 
 The numbers of bacteria, as determined in this way in 
 natural waters, vary greatly. A water taken directly from 
 the ground, at a depth of six feet or more, should contain 
 none. In good pond waters may be found anywhere from a 
 few score to a few hundred. In polluted streams they may 
 run up well into the thousands or hundred thousands, and 
 in sewage they can be sometimes counted in the millions. 
 Organic matter is composed of carbon, hydrogen, oxygen, 
 and nitrogen ; at least, for our purpose it will suffice if we 
 so consider it. It is only the nitrogenous organic matters 
 
10 
 
 which undergo those kinds of changes which we include 
 under putrefaction, and which we regard of importance 
 from a sanitary standpoint. Familiar examples are milk 
 and meat, which, when exposed to the air, become offensive, 
 but starch and sugar (which contain no nitrogen) do not. 
 
 The nitrogen which we find on analysis from undecom- 
 posed animal and vegetable matter, say fresh albumen, we 
 call " organic nitrogen," by which we mean that the nitrogen 
 is still in its original combination before change or decay 
 has set in. Leaving out of consideration that present in 
 rain-water, we may say that ammonia in water is distinctly 
 characteristic of the first stage of the decomposition of 
 organic matter. The term " organic nitrogen " has been 
 used, but on the tables of analyses another is substituted, 
 namely, "albuminoid ammonia." It is an unfortunate fact 
 that the methods of determining organic nitrogen have been, 
 until recently, very tedious and difficult, and not always 
 reliable, so that chemists have resorted to another process, 
 which gives only a part of the organic nitrogen in the form 
 of ammonia. That is called albuminoid ammonia, because 
 albumen, when subjected to this process, gives up its nitro- 
 gen as ammonia. 
 
 From the present methods of examining water the 
 following facts are ascertained, (i) By means of the micro- 
 scope, the kind of life existing in the water, from which 
 conclusions are drawn as to the kind and quality of the 
 food which supports this life. (2) By means of the gelatine 
 plate cultures, the number of the bacteria in the water, 
 from which conclusions are drawn as to the amount and 
 kind of decay going on. (3) The purely chemical examination 
 reveals directly the amount of organic matter, and the con- 
 ditions in which it exists. These widely different methods 
 are merely different points of view. It is one and the same 
 thing throughout, namely, the life processes which are 
 going on in the water ; for decay is but the manifestation 
 of another form of life. 
 
 If it is asked why study is centered here, the answer is, 
 simply, that experience has taught that it is the organic 
 matter which is the cause or accompaniment of disease ; it 
 is during the decomposition of this organic matter, and in 
 
II 
 
 some of the changes it undergoes in the process of decay, 
 that danger lurks. This is the chemical expression of the 
 causation of disease. The biological expression takes an- 
 other form, namely, that the bacteria which cause changes 
 in the organic matter cause also disease. The two expres- 
 sions do not contradict each other, but go hand in hand. 
 The chemical idea implied in both expressions is that the 
 state of change is the state of danger. From an horticul- 
 tural point of view, the state of change is the state of evo- 
 lution. 
 
 The vegetable mold which forms the rich top-soil of 
 every agricultural country consists of a very uniformly fine 
 mass of blackish color, usually only a few inches in thick- 
 ness, though under exceptionally favorable circumstances it 
 may reach a depth of nine or ten inches. Humus (of which 
 there is a surprising lack of definition in the best works, but 
 which is generally understood to be earth more or less 
 charged with decaying organic matter) is well illustrated by 
 beds of peat and so-called muck. The latter term, however, 
 according to Storer, is misapplied, and should mean " well- 
 rotted dung " (II, 78), though in this country, and especially 
 in New England, it is synonymous with marsh mud. The 
 vegetable mold, if not coincident with, at least contains 
 the greater part of the humus in a given area, and it is in this 
 that the germination of seeds and the growth of plants have 
 their best development. 
 
 The humus has been investigated by our countryman, 
 Prof. A. A. Julien (" On the Geological Action of Humus 
 Acids." Pr. A. A. A. S., XXVIII, 1879, 311), by whose 
 labors it is established that there are many acids of com- 
 plicated constitution confounded under the name humic 
 acid. All of them act energetically upon rocks, and per- 
 form important functions in the preparation of the material 
 with which they come into contact to facilitate plant 
 growth, directly through the disintegration of leaves and 
 animal tissue, and indirectly by furnishing food to the 
 bacteria which are so indispensable to vegetable life. 
 
 Charles Darwin, among the countless contributions of 
 this greatest of naturalists to our understanding of nature, 
 has observed (" The Formation of Vegetable Mold 
 
 L.oFC 
 
12 
 
 through the Action of Worms," etc.; Appleton, 1882) that 
 the upper part of the intestines of earth worms generates 
 the several humus acids which are produced by decaying 
 vegetation. The calciferous glands lying below this tract 
 produce a material which neutralizes the acids thus gener- 
 ated, for the digestive fluid of worms will not act unless 
 it be alkaline. These acids, he thinks, are generated during 
 the digestive process, and are probably of nearly the same 
 nature as the humus acids, so that the agency of worms in 
 producing the material out of which that of plants is 
 assimilated is evident. The action of worms is not con- 
 fined to chemical changes, but extends in many widely dif- 
 ferent directions, and, according to this accurate observer, 
 is stupendous in its results. At the risk of repeating what 
 is familiar to many of you, I will sketch briefly this action 
 as epitomized in the work just cited. There are but few 
 genera of earth worms distributed throughout the world. 
 /Their mode of life is to burrow in the ground, which they 
 do by eating a hole through the soil, and with the mouth 
 filled, advancing the oesophagus, thus forcing the cheeks 
 outward in all directions, crowding the soil aside, and en- 
 larging the burrow. (" The Soil," etc., F. H. King, Pro- 
 fessor Agricultural Physics in University of Wisconsin ; 
 Macmillan & Co., 1896.) The material swallowed is passed 
 through the calciferous glands lying midway in the oesopha- 
 gus, where the acids are neutralized; through the crop and. 
 gizzard, where the particles are triturated by the hard stones 
 habitually retained there ; and into the intestine, where the 
 pulp is again made acid ; whence, at the mouth of the bur- 
 row, it is, voided in the form of castings or worm-dung in 
 piles of greater or less size, and more or less retaining the 
 mold of the intestines. The castings may be seen after a 
 rain, especially in gardens and much-frequented walks. 
 Earth worms work preferably at night, and lie close to the 
 mouths of their burrows by day. The mouth of a worm is 
 situated at the anterior end of the body, and by means of a 
 lip the animals can grasp an object and draw themselves 
 forward. Their intestine has a deep involution of its walls, 
 by which additional absorbent surface is gained. They 
 breathe through the skin. They are destitute of eyes, but 
 
13 
 
 conscious of a bright light and sensitive to it in the anterior 
 part of the body. They are less sensitive to radiant heat. 
 They are very sensitive to touch or vibration, though not 
 to sound. Their perception of odors is feeble, but enough 
 to direct them to objects which they like to eat (cabbage 
 leaves, onions, etc.). 
 
 They are omnivorous, swallowing everything they can 
 grasp, and extracting what nutriment the mass contains. 
 Their preference is for half-decayed leaves, however, which 
 they draw into their burrows partly for food and partly to 
 close the entrances ; and to this circumstance is due much 
 of the finest soil which they produce. 
 
 They moisten the objects with a secreted alkaline fluid 
 like pancreatic juice. The calciferous glands are probably 
 fed with lime by the leaves in which this earth concentrates 
 before they fall. This is excreted as carbonate of lime and 
 aids the digestive process. The castings of worms are 
 usually acid. Darwin concludes that they possess a low 
 order of intelligence, in contradistinction to instinct. His 
 experiments on this subject are very curious and instructive. 
 With worms kept in a pot he observed the manner in which 
 hundreds of objects of different shapes were drawn into 
 their burrows, which are thus lined, he thinks, on account 
 of the sensitiveness of the animals to cold, for the purpose 
 of avoiding the contact of their bodies with cold, damp 
 earth. The amount of work performed by worms is meas- 
 ured by the rapidity with which objects laid on the ground 
 become covered by their castings. There are instances of 
 coal ashes, strewn over a large field, which were buried in 
 this way 7 inches in eighteen years. The tesserae of pave- 
 ments, ancient buildings, large stones (including some of 
 the Stonehenge), ancient walls, etc., are found to be covered 
 to a greater or less depth by the castings of earth worms, 
 and independently of the action of other agencies. With 
 this, of course, is to be reckoned the sinking of these objects 
 through undermining by worms, and the subsequent colapse 
 of the burrows. The soft mold removed from lower levels 
 to the surface has passed repeatedly through the intestines 
 of worms, and much of it has been finely triturated in their 
 gizzards. Darwin estimates that, in each acre of earth 
 
14 
 
 which is sufficiently damp and not too sandy, gravelly, or 
 rocky for worms to inhabit, a weight of more than 10 tons 
 of earth annually passes through their bodies and is brought 
 to the surface. The result for a country of the size of Great 
 Britain in, say, a million years, is 320 million million tons of 
 earth in land which is cultivated and well fitted for these 
 animals. It is probable, he thinks, that all of the finest 
 vegetable mold which we see has passed again and again 
 through the bodies of earth worms. 
 
 There is a series, and perhaps a cycle, of changes from 
 the partially cooled, still incandescent mass, and newly 
 formed planet — the Earth* — to the well-cultivated hive of 
 industry of to-day ; teeming with millions of workers prose- 
 cuting countless industries, all of which depend upon the 
 change of form of the materials which the earth furnishes, 
 sometimes for the sake of these new forms, and sometimes 
 for the sake of the forces which are incidentally generated ; 
 but all of which are made possible by the life which the 
 earth gives to the workers through the products of its soil. 
 
 (1) There was the partially cooled, lava-like crust of the 
 earth, glowing cherry-red, and surrounded by the heavy acid 
 vapors and steam, wherein the volatilizable oxygen com- 
 pounds of sulphur, phosphorus, nitrogen and the like, known 
 as sulphuric, phosphoric, and nitric acids, pervaded and gave 
 
 * A new view of the evolution of our planet eliminates incandescence and 
 change from gas to liquid and from liquid to solid during the earth's history. 
 [T. C. Chamberlm, Journal of Geology, vi, 609; vii, 545, 667, 752. H. Le Roy 
 Fairchild, Bui. Geol. Soc. Am., vol. xv.] According to the modern substitute 
 hypothesis the discrete matter derived from the hot nebular ring was cooled 
 before it aggregated to form the earth. But even if this new view should ulti- 
 mately displace the assumption that the earth was a hot fluid ball, which so 
 many distinguished geologists have considered the necessary consequence of 
 La Place's Nebular Hypothesis, it will not in any way affect the proposition of 
 the interdependence of various forms of life herein stated. Neither the old 
 nor the new hypothesis of the origin of the earth pretends to account for the 
 advent of life, and its dawn is almost universally ascribed to a time when the 
 surface of the planet was not greatly warmer than it is now. The only differ- 
 ence is that the new theory gains the disposal of an immensely greater period 
 of time during which this earliest life may have been evolved into the many 
 forms existing to-day, and shakes itself clear of the fetters which Lord Kelvin 
 and other physicists have put upon geological speculation. Professor Fair- 
 child's plea is " Geology for the geologists ! " 
 
15 
 
 their acid character to the dense, inky clouds of steam 
 mingled with all other but the most unvolatilizable terres- 
 trial elements. 
 
 Finally, when additional cooling' had taken place, these 
 acid vapors condensed and descended in torrents which ex- 
 coriated the vitreous mass, and sent floods of highly satu- 
 rated solutions into its natural depressions — the first com- 
 mencement of a sea. The waters heretofore enveloping this 
 planet in clouds like those of Mercury and Venus, descended 
 in great mass and deluged the basaltic crust, cracking and 
 comminuting it, and thus offering the acids more favorable 
 opportunities to attack and dissolve its substance ; tearing 
 away its salient prominences by crush of flood and gale ; 
 spreading out the debris as a slime, mud, or sand in the 
 natural channels ; and carrying the finest suspended particles 
 into the sea. At last, the alkaline ingredients neutral- 
 ized the acid waters, and the ocean contained only highly 
 diluted neutral salts. 
 
 The contraction of the nucleus produced new elevations 
 and depressions, changing the old ones ; so that continu- 
 ously the bottoms of the seas emerged and became dry land, 
 and high ridges were depressed under the surface of the 
 waters. Somewhere, either at this period or perhaps from 
 the very beginning, appeared the force we call life because 
 we cannot understand it ; and in all probability its lowest 
 known form — perhaps some sort of bacterium. The deriva- 
 tion from this simplest life-element of the lowest life-king- 
 dom we recognize — that of plants — is not yet understood, 
 but the advance accomplished, as always occurs in nature, 
 the plants assisted, and were assisted by their predeces- 
 sor in form, until still further progress was made ; each 
 stepping-stone being used as a support to place the next, 
 while the old were not destroyed ; just as a man flings blocks 
 into a stream to cross dry-footed, and stands on the last he 
 has planted to place the next. 
 
 Then plant-growths imperceptibly changed in complexity 
 and character to the second and highest life-kingdom — that 
 of animals ; but so insensibly, and with so many interlock- 
 ing characteristics among the beings which are found on the 
 border line, that no definition has yet been found which can 
 
i6 
 
 quite satisfactorily indicate the distinction between animal 
 and plant, nor between plant and mineral, nor between vital 
 and any other kind of force. 
 
 Taking the sequence of events as they are, the infinite 
 variety of plant and animal forms, from the minutest unit 
 capable of being seen under the microscope to the gigantic 
 California redwood, and the elephant, the lower forms and 
 forces act as servants to the higher. The winds and frosts 
 still tear new mineral matter apart, and the rivers and 
 ocean grind, sift, and spread it into gently sloping prairies. 
 The micro-organisms and the fungi invade this material, 
 and, reaching to the atmosphere for the organic elements 
 which it contains, translate this carbon and nitrogen into 
 lichens, moss, herbs and humus. But with this' advance 
 in the vegetable world an advance in the animal world 
 has taken place pari passu, and, amongst other useful 
 forms, the worms appear as husbandmen and workers of 
 this crude mass into soil fit for the highest plants. Again 
 and again this comminuted dust, with its bacteria, goes 
 through the alimentarjr canal of the worm, and is spread 
 over the surface, hard or soft, sterile or fertile alike, hid- 
 ing the floor of our planet under the rich banquet which 
 these humble creatures spread out for higher forms of the 
 lower kingdom. 
 
 Upon this spring the grasses and grains, the bushes and 
 trees, which in turn send down their roots through the soil, 
 and, saturating the unaltered crystalline rocks with their 
 acids, prepare new material for the steps of preparation 
 which have been described. On the higher forms of plant 
 life the highest forms of animals live, the highest as 
 well as the lowest representatives supplementing their 
 simpler diet by feeding on each other. 
 
 The processes are so various, the change of action so 
 incessant, and in such endless rotation from purely physi- 
 cal or chemical to vegetable and animal, that one is unable 
 either to specify in what resides the high and the low in 
 nature, or wherein the forces or the forms we recognize in 
 the three kingdoms differ from each other fundamentally, 
 in spite of the superficial differences which appear to our 
 senses. 
 
Ik 
 
 rag 
 
 mm