THE FUNCTION OF TANNIN. 
5 
SOME INVESTIGATIONS INTO THE FUNCTION OF 
TANNIN IN THE VEGETABLE KINGDOM. 
BY W. HILLHOUSE, M.A., F.L.S. 
( Continued from Vol. X ., page 309). 
The distribution of tannin in winter stems has been 
described by Sanio* in a few selected cases. In its general 
distribution, as seen in my own investigations, it is met 
with alike in assimilating tissues, such as leaves and cortex, 
and in storage tissues, such as medullary rays and pith in 
winter, and in the tissues of the leaf bases from which 
deciduous leaves have fallen or are about to fall. While 
generally present in the cell-sap of nearly every cell of 
the tissue concerned, tannin not infrequently has a definite 
distribution, as for example in vertical rows of elongated cells 
in the soft bast of Phaseolus multiflorus (kidney bean), in 
special tubular tannin vesicles of considerable length in the 
cortex and outer pith of Sambucus nigra (elder), and, together 
with starch, in cells forming a reticulum amongst the inner pith 
cells of very many dicotyledonous trees. Like starch, it is 
far less common in the aerial stems of Monocotyledons. 
This constant association of starch and tannin is curiously 
substantiated by Ebermayer :—“ A lie guten Gerberinden sind 
ziemlicli reicli an Starkemelil.” f In general terms, my 
observations on the distribution of tannin tend to show that 
its presence in living tissues may be classified into— 
(1) In cells containing protoplasm and little starch, or 
starch in minute grains; 
(2) In cells containing starch, as reserve stores, and 
little protoplasm. 
Cases of the first are generally cortical cells, and cells of 
the soft bast and bast rays. In these the whole contents of 
the cell, under the action of potassium bichromate, tend to 
collect into either a large ball, or a number of balls, of clear, 
bright, oily looking substance, highly refractive. In these 
cases it is probably always dissolved in the cell-sap, and in 
the interior of the protoplasmic body of the cell; under the 
action of the reagent this latter is killed, and more or less 
contracted; the tannin becomes partially diffused throughout 
the protoplasmic mass, partly passes outside it; the balls 
and masses formed by the reagent may, therefore, involve 
* Sanio , “ Einige Beobachtungen,” u.s.w.; Bot. Zeit., 1863. 
f Ebermayer , Phys. Chemie der Pflanzen, 1882, Bd. I., p. 404. 
