1915] COOK & WILSON—ENDOTHIA PARASITICA 351 
These considerations naturally raise the question of the acidity 
of the culture medium containing tannic acid. Our tests showed 
that a 3 per cent aqueous solution of tannic acid is about +65 
Fuller’s scale. This is considerably higher than is indicated by 
CLINTON (Report Conn. Agric. Exp. Sta. 1912. p. 432). However, 
as CLINTON used a vegetable (potato agar) medium, while we used 
a synthetic medium, the results are in no wise comparable, 
as no account is taken by CiinTON of the effects on the tannic 
acid of the various organic constituents of the medium to which he 
added it. 
Gallic acid was similarly tested, but failed to show any coagu- 
lating effect either on the agar medium or on its constituents. 
The various materials furnished by Kerr behave in much the 
same way toward agar as does commercial tannin. His purer 
tannin extracts, however, do not liquefy the agar at as low percent- 
ages as does commercial tannin. Those extracts from which the 
coloring matter had not been removed had a more pronounced 
action on the culture medium than even the second lot of MERcK’s 
tannin. The original acidity of the agar and the quantity and 
nature of the impurities which may be present in the tannin appear 
to modify to a great extent the chemical activities upon the admix- 
ture of the two substances in completing the culture medium. 
To test tannin fermentation 
To test the ability of the fungi to live in pure solutions of tannin 
and related substances, two experiments were made with varying 
strength of aqueous solutions of these materials. In the first 
series, the spores were sown on the medium, and after germination 
cubes about 5 mm. in size were transferred to the tannin solution. 
In these tests E. parasitica and the European strain of E. radicalis 
were used. 
The first test included Mercx’s tannin and Kerr’s extracts 
“A” and “1—X,” of 2.05 per cent and 5 per cent solution. The 
strength of the solution appeared to have less effect on the fungus 
than did the nature of the material. The two species of fungi 
showed no more difference in quantity and vigor of growth than 
would be expected for two strains of the same species. 
