oDDOQoaDQDnDDDoaDODDaaaoDODOoana D D D D D D d j0 «i!^ a a s ^&% a d s ram & % a D > m VcT /h ™ D D z la\vt( /g? 5 D D •? toMMS' f D a a a d D D UNIVERSITY OF MASSACHUSETTS g LIBRARY D D D D D D LJ U a a a d D D M B R 1896. B R $647 R D D D D Archives Thesis g D D D D D D D D D D D D D D D D D D a D D D ffln n D D a D D D ■DOQaQDQDDODOaaoaDODaDODDDDaaOOQa THE TANNING PRINCIPLE OF PLANTS BY fRJSDERIQ J. SMIT1 nr 1896 k BRIEF ABSTRACT I! II I '< ■ F ETTS AWHEvvST, Vi ; ° The tanning or astringent principles are widely distributed in plant life and infusions of those parts rich in tannin have long been used in the art of converting animal hides into leather. Since Deyeux discovered and separated C-allo-tannin acid from gall nuts in 1795, the tannins have n oeen the subject of much investi- gation by chemists. In the study of plant life, the Botanists have also endeavered to discover what role the tannins play in plant physiology. Hence a study of tannins form a good topic for both branches of science. ,Vhile the microscope was used to make qualitative tests for tannins over a wide range of native and cultivated plants, the qualitative determinations have been confined to two species of native forest trees, viz:- the hemlock Spruce (Abies Canadensis) and the .'."hite oak ( Quercus ilba) , and which are used as commercial sources of tannin. Specimens of these trees were selected and continued under observation as long as materials were needed to carry on the work. Samples of bark wore taken from different size trees beginning with the larger roots, and from the trunks as near the ground as practicable; also midway and near the top. Samples were taken from the same specimens in October, January and in the spring when the sap had started to flow. Microscopical examinations on the freshly gathered materials showed the presence of tannin in the bark from all parts of the trees of both species. The woody portions of the Hemlock Spruce did not respond to the test as did the Oak. The richness in tannin of the medullary rays in the smaller oak roots is especially worth noting. j.q.n jo -?TiiuuBq. ciiJ Tannin bodies mixed with starch grains (resembling potato starch) was a very prominent feature in the cambrium of small Hemlock roots, while the tree^was dormant. Notable also was the abundance of tannin in the opening buds of the oak. The analytical tests were performed by the Lowenthal , volumetric and Proctor's powdered hide methods for comparison. Analysis shows the storage of tannin greatest in the base of larger and older portions of trees of both species, arid the bark of the larger was especially rich, often showing double the percentage of tannin than bark from the same trunk. There seems to be little seasonal variation of the distri- bution of tannin in the bark and the custom of felling trees for their tannin in the spring when the bark will peel readily can be followed without loss. Whether it would be economical to pull the stumps and secure the richer tan bark of the roots would depend on local conditions or if the land were to be cleared for agricultural purposes. From the fact that tannins have a strong attraction for oxygen, as well as albuminous matter, and their tendency to form glucosites with grape sugars suggests their function in the plant is to assist in assimilation, acting possibly as a reducing agent in the growing tissues and as a means of storing reserve nutrients in the more dormant plants. That its activity in growing tissues is of short " a inn may be assumed, as tannin bodies are found in abundance- in tissues t] at have 3eased to ;r , ich 3 as lea some botanists to believe they are a by-rproduct and not an sssential to tl • '. i ; tissue. imiireq. ni sseuqoxj &m -WJL / IsLs-UWlAsvx^A T C -C <> ■ -< -. < / * l \ C \ I C'L C i . i L l^ i i t v i- ^cf ''**■ <• c * ^t i v x (7^C~»-«- /IL< ~*^ CC .-*-«-» v. V » i * Z' r^4 ' i i. M *^t »^ . *- i. x <- *- * .♦■ *- «. v 1 - *~ i*,%% L. lU~OVL H*" U { 6 *-, **<* 1 V- \ !.«.*.-<-- 1 t •* vi.' kT 1 4 «•- v-v *- wt>^ v - /*■ i -»-\^ /- i 4L -Ci? *- Hf i V fc ">~-Zf » a. vr w -< t "V c«< I VI «. i a «- ixl C « ■ - ' - *- V C- i / / i' . ,i v. , syz La. ,. ,i^i K. «— ^* / i i *-*. V , i V- \ \ »- »- v *- «- ' ^ *- *-*- 1 V ■ r f /• C<-t I < 4 ^ — -*. 4- L. < (UA-'t- j£ i t -«_-< , . _ — :> .V 4 / I