1915] COOK & WILSON—ENDOTHIA PARASITICA 357 
of the American strain. Pycnospores were not found on either the 
check or the cultures containing tannin. 
E. radicalis (CLINTON’s E. gyrosa no. 7674) made a fair growth 
on 0.2, 0.6, and o.8 per cent, and a slight growth on the higher 
percentages. The growth generally increased on all cultures, but | 
was always subnormal; no pycnospores were found. 
E. radicalis mississip piensis grew on only the o.8 per cent extract 
during the first week. In 10 days there was good growth on both 
o.6 and o.8 per cent, fair growth on 1 and 1.6 per cent and slight 
growth on 2 and 2.8 percent. The growth increased on all cultures 
during two months’ observation, and pycnospores were produced 
‘in abundance on all cultures up to 2 per cent. 
In general it may be said that E. parasitica and E. radicalis 
thrive fairly well on cultures containing these extracts, but not 
so well as on the checks. The American strain of E. parasitica 
is more resistant that the Chinese strain, and E. radicalis mississip- 
piensis is the most resistant of any species used. 
KeErrR’s extract ‘“‘A”’ is a compound of various forms of tannin 
and of other more or less related substances. It represents about 
9 per cent of the dry weight of the bark. Its es. is as 
follows: tannin (containing the forms represented as “1—X,” 
““2-X,” and ‘‘3-X”’) 60 per cent, fermentable sugars 10 per cent, 
gallic acid 7 per cent, pentoses and pentosans 8 per cent, water 5 
per cent, undetermined 10 percent. This extract produces a rather 
advanced proteid digestion, causing the agar to become semi- 
fluid, and in the higher percentages used a considerable amount of 
fluid was present. The series included 1, 1.2, 1.6, 2, and 2.4 per 
cent of the extract. Sowings were made with E. radicalis (CLIN- 
Ton’s E. gyrosa no. 7674) and E. parasitica (STEVENS no. 1158). 
E. parasitica (American) made a slight growth on all cultures 
during the first week. In 10 days the growth was good on all 
cultures up to 2 per cent. After that time the growth was slow. 
At the end of the first month pycnospores began to appear on 
cultures containing 1 per cent, but did not appear on others. This 
organism made its best growth on this medium. 
E. radicalis (CLunton’s E. gyrosa no. 7674) made a slight growth 
on cultures up to 1 per cent. The growth was poor throughout 
