1915] COOK & WILSON—ENDOTHIA PARASITICA 347 
the cells of the host to form auto-bodies which destroy such enzymes 
or toxins, to excrete chemotactic substances which expel or attract 
the fungus protoplasm.”” 
The little work that has been done indicates that these problems 
involve both plant pathology and plant physiology, and that the 
plant pathologist must give more and more attention to the funda- 
mental problems in plant physiology. 
Some years ago the senior author and Dr. J. J. TAUBENHAUS 
conducted a series of experiments on the relation of parasitic fungi 
to the cell contents of the host plants.3 The primary object of this 
work was to determine to what extent tannin might be a factor in 
enabling the host plant to resist parasitic fungi. Although the 
fungi which attack fruits were used for most of these experiments, 
some attention was given to Endothia parasitica. This organism 
gave a good growth of mycelium and scant spore formation when 
grown on an agar medium containing 0.6 per cent tannin, but a 
less toleration to tannin when grown on a liquid medium. It was 
also evident that its toleration of tannin was somewhat dependent 
on the character of the food supply. 
A little later, CLINTON‘ made similar experiments with Endothia, 
using commercial tannin (M. C. E. Brand, U.S.P.) in amounts 
varying from 0.2 per cent to 14 per cent. All cultures grew in 
media containing as high as 4 per cent tannin; about one-half of the 
cultures of E. gyrosa grew on media containing 8 per cent tannin, 
but all failed to grow on cultures containing more than 12 per cent. 
E. parasitica was a little more tolerant to tannin than the other 
species used. CLINTON used a potato agar, and therefore his 
results are not comparable to those obtained by Cook and TAuBEN- 
HAUS, who used synthetic media. 
Although the results of all of these studies indicate that tannin 
is in a measure toxic to fungi, the report of the chemist of the 
2 MARSHALL-Warp, H., Recent researches on parasitic fungi. Ann. Botany 
I9:I-54. 1905. ‘ 
3 Cook, MEL. T., and Tausennavs, J. J., Relation of parasitic fungi to the 
cell contents of the host plant. 1. Toxicity of tannin. Delaware Agric. Exp. Sta. 
Bull. or. pp. 77. figs. 43. 1911. 
4 Curnton, G. P., Chestnut bark disease, Endothia gyrosa var. parasitica (Murr) 
Clint. Ann. Report Conn. State Agric. Exp. Sta. 1912. pp. 359-453. pls. 21-28. 1913. 
