10 
THE FUNCTION OF TANNIN. 
passages, moderately in the other cortical cells, considerable 
quantity in the bast, especially the outer bast, and a fair 
quantity in the pith. The young tissues of the bud have 
nearly every cell full; the bud scales are full. 
For some time, about every week. I examined this stem ; 
there was an undoubted diminution of the tannin ; (1) in the 
bast, (2) in the cortex, (8) in the tissues succeeding from the 
bud ; the bud itself remained full. Testing the stem with 
alkanet, showed that this decrease of tannin proceeded pari 
passu, with an increase in the amount of resin; the cells 
surrounding the resin ducts always showed the free presence 
of tannin. 
According to Schell, starch and oil are wanting in the 
stem of Finns sylvestris. This is not entirely the case. 
A few of the ray cells, both in wood and bast (on November 
24th), contained starch in very small elongated grains. Some 
outer cells of the pith contained much larger grains, tending 
to kidney shape; many of the cells surrounding the resin 
passages of the wood (not of the cortex) also contain starch. 
On the other hand, most of the cells of the cortical tissue and 
bast contain a considerable amount of glucose, though this 
may be partly produced by the decomposition of the tannin 
in the reaction. 
The tannin of Fmus sylvestris therefore may have relations 
with the copious resin formation of spring, but not with the 
building of new tissues. 
I have not investigated Larix europcea, where Schell also 
says tannin is used as food material. 
The rhizomes of S colop endrium vulgare and of Nephrodium 
sp. showed (April 21st) abundant tannin in the starch 
parenchyma, as well as in the parenchyma of the vascular 
bundles ; with further development this does not disappear or 
diminish, but seems rather to increase. 
Fuchsia (hardy out-door) showed, May 30th, its root stock 
and young stems alike with abundant tannin. Made to 
grow in the dark, its tannin showed no signs of diminution, 
even when the starch was quite exhausted, and the plant 
gradually died from exhaustion. 
Young plants of Fuchsia grown in a stove, and forced to 
grow in the dark from May 28th till complete exhaustion 
(with various specimens from June 28th to July 17th) showed 
no apparent diminution in the tannin contents. 
Digitalis purpurea also, grown under a dark shade from 
May 23rd to June 19th, showed no diminution in the tannin 
present or once formed, whether in its root-stock, or in its 
stem (in which the tannin is mostly found in the angles of 
