356 BOTANICAL GAZETTE [NOVEMBER 
of ae bark, which under ordinary methods of analysis is estimated 
“tannin,” is more toxic than commercial tannin. KERR in 
oonatae on these results, says: 
The action of ‘‘3—X”’ is also surprising, as it is what we term the coloring 
principle of the bark, the exact nature not having been determined by anyone 
that I know of. Its action brings out a rather interesting point, and that is 
that chestnut trees of northern growth, say on a line north of the southern 
boundary of Pennsylvania, contain very materially less coloring matter than 
the growth south of it, and, as we all know, the wood in the-latitude referred 
to seems to have been more susceptible to the disease than that further south 
{letter December 26, 1913]. 
GROWTH ON COMBINATION OF KERR’S EXTRACTS 
Since “‘1—X,”’ which is a tannin extract, was stimulating, and 
“*3-X,” which is primarily coloring materials giving tannin reac- 
tions, was toxic, it was decided to combine the two into one extract. 
The material was made up into a series of cultures containing 
0.2, 0.6, 0.8, 3:2, 1.6, 1.8; 3, 2:2; 7:4, 2.6, and 2.8 per cent 
Sowings were made with E. radicalis (CLINTON’s E. gyrosa no. 
7674), E. radicalis mississippiensis (STEVENS no. 2424), and both 
American and Chinese strains of E. parasitica. 
There was a tendency for the agar containing as much as 1.2 
per cent of the extract to become less solid, but even with 2.8 per 
cent there was no approach to a real liquid condition. 
E. parasitica (American) made a fair growth on 0.6 and 0.8 
per cent in one week, with a slight growth throughout the series 
except on 0.2 and 2.2 per cent. The growth increased, but was 
relatively the same on the different cultures throughout the entire 
period. During the third week pycnidia appeared on 0.6 per 
cent, and by the end of the fifth week had developed on all cultures 
up to 2.2 percent. In cultures containing more than 2.2 per cent 
the pycnospores decreased. The growth was always subnormal, 
but not so pronounced as in some other cultures. 
E. parasitica (Chinese) also failed to grow on 0.2 and 2.3 per 
cent, but made some growth on 0.6, 0.8, and 1.2 per cent during 
the first week. At the end of the second week the cultures con- 
taining o.6 per cent showed a subnormal growth, and the2.8 per 
cent a very slight growth. The growth generally was less than that 
