82 
THE FUNCTION OF TANNIN. 
And yet nine out of ten people still think of photography as 
simply a mechanical method of taking portraits. Let it be 
the task of photographers—and more especially of amateurs 
—to show of what infinite applications, and those of the 
highest and most accurate nature, photography is capable. 
SOME INVESTIGATIONS INTO THE FUNCTION OF 
TANNIN IN THE VEGETABLE KINGDOM. 
BY W. HILLHOUSE, M.A., F.L.S. 
(Continued from page 11.) 
I germinated, alike in light and darkness, the following 
seeds, viz.:— Cynoglossum officinale , Vicia Faba, Ricinus com¬ 
munis, Phaseolus multifiorus, and Helianthus annuus , growing 
each, in the experiments in darkness, up to exhaustion point. 
Cynoglossum vulgare in which, according to Schell, the 
tannin produced during germination is subsequently used up, 
I fully germinated. The testa of this oily seed contains no 
tannin; in the cotyledons, however, a certain amount is 
present. In the seeds germinated in light, a continuous, but 
variable, increase in the amount of tannin present is manifest. 
In those grown in darkness, the earlier stages of germination 
are likewise accompanied by an increase in the amount of 
tannin produced, but as the reserve food stores become 
exhausted, and no new food materials result from chlorophyll 
action, the contents of the cells become progressively more 
watery, and an apparent diminution of tannin contents takes 
place, but it is not at all clear whether this results from 
greater dilution or actual diminution. A comparison of the 
etiolated with the non-etiolated material gives distinctly the 
presence of larger quantities of tannin in the latter, but this 
by no means necessarily implies usage of the tannin in the 
former, owing to exhaustion of the food supplies, but may be 
due to no secondary food formation, with its accompanying 
tannin formation, taking place. 
Vicia Faba is specially interesting owing to the tendency 
for tannin, here highly coloured brown, to accumulate in 
vertical rows of cells in the neighbourhood of the vascular 
bundles, especially in the primary root. In the lateral roots 
this is much less markedly the case. In the testa there is 
abundant tannin, and this in the process of germination 
undoubtedly largely diminishes, but here also an element of 
doubt comes in, as to whether the diminution is not due to 
