360 BOTANICAL GAZETTE [NOVEMBER 
(c) E. radicalis (including E. gyrosa) was very susceptible to the 
influences of tannin. 
g. Tannin (MERCK) affects the various species of Endothia very 
differently. E. radicalis (including E. gyrosa) is inhibited; E£. 
parasitica is at first retarded and later is able to feed on the tannin; 
E. radicalis mississippiensis is practically unaffected and does not 
feed on tannin. 
10. Analyses of chestnut bark made by Kerr show a corre- 
sponding tannin reduction in diseased areas, which confirms the 
culture experiments and makes it possible to state that E. parasitica 
is able to use the tannic acid for food. 
11. E. parasitica appeared to have its power of pycnidia pro- 
duction stimulated by commercial tannin and the true tannin 
extracts of chestnut bark, but reduced or inhibited by those extracts 
of chestnut bark which are composed almost entirely of coloring 
substances, but which are present in tannin extracts and estimated 
as tannin. 
12. Specially prepared extracts of pure tannin were either 
stimulating or only slightly toxic when combined with coloring 
materials and other substances associated with tannins and respond- 
ing in the same or in a similar manner to tannins. (a) KERR’S 
“7X” extract has a stimulating effect on E. radicalis (E. gyrosa) 
and E. parasitica. (b) KERR’s ‘‘2~X”’ extract has a tendency to 
retard E..radicalis (E. gyrosa), E. parasitica (both American and 
Chinese strains), and E. radicalis mississippiensis. (c) KERR’s 
3-X”’ extract was extremely toxic to E. radicalis (E. gyrosa) and 
Py parasitica. (d) In E. radicalis (E. gyrosa) conidia production 
was at its maximum at 1-1.2 per cent of the extracts designated 
“7X,” “2-X,” and “3—X,” while but few if any pycnospores were 
produced on the other substances used. (e) The European strain 
of E. radicalis showed similar results, but the American strain 
showed a tendency to remain sterile. (jf) A combination of “1—X” 
and ‘‘3~X”’ is somewhat toxic, but the toxicity of “3—X”’ appears 
to be largely overcome by the stimulating influence of ‘“‘1—X.” 
E. radicalis (E. gyrosa) and E. parasitica were slightly retarded, 
and E. radicalis mississippiensis was very slightly retarded. The 
Chinese strain of E. parasitica was less resistant than the American 
