406 CONNECTICUT EXPERIMENT STATION REPORT, 1912: 
Barnes (Textbook of Botany, 1, p. 414) says concerning this 
subject: “Some substances, including the loose term tannin, 
are glucosides, and such as can be made to yield glucose by 
digestion may be considered as plastic substances rather than 
wastes.” Stevens (Plant Anat., p. 205) also states: “Tannins 
seem to be by-products, set aside in the tannin cells from the 
general circulation. It is uncertain whether the tannins are 
ever used to an appreciable extent in nutrition. They seem to 
be of service, however, in warding off parasites by their aseptic 
qualities and astringent taste.” 
Cook (Delaware Agr. Exp. Sta. Bull. 91, p. 59), who studied 
the effect of tannic acid on different species of fungi in 
artificial cultures, says in his general summary: “It appears 
that tannin is an important factor, and that its importance varies 
in accordance with the other substances with which it is 
associated in the cells of the host plant. While tannin no doubt 
serves'as a protective agent, its efficiency in this ‘direction will 
vary somewhat with the character of the other substances within 
the cell. This may account for the variation in power of 
resistance between species, varieties, and individual plants. The 
fact that plants which produce large quantities of tannin are 
subject to disease is no argument against the preceding. The 
organism may live in tissues which bear little or no tannin, or 
which contain other substances that in a measure counteract 
the influence of the tannin. Furthermore, some species of fungi 
are much more resistant to tannin than are others, and the species 
which attack these high tannin-bearing plants no doubt possess 
this quality.” 
To the writer it has occurred that possibly tannin may serve 
as an. unusual source of food for certain trees rich in this 
product under unfavorable conditions for active formation of 
their normal food supply, such as drought years, and that such a 
use would lessen the supply of tannin laid down in the annual 
growth of wood formed in these years. Or possibly if not 
used for food, these unusual conditions do not favor its normal 
production. In any case, if tannin content bears a relation to 
the blight disease, it is not the tannin of the whole tree that 
counts so much as the tannin of the bark and wood of that 
year’s growth. If it bears any relation to the chemical activity 
of the tree, we can readily see that it could easily vary from 
