Physiology of the Genus Eicl ami a. 431 
7. The growth-limits in relation to hydrogen-ion concentration for the 
media used are as follows: 
E. catemdata pH j-i 6 and pH 8-2, 
E. viridescens pH 2 and pH 8*2, 
E. acremonioides pH 3 approx, and pH 8. 
8. E. catemdata and E. viridescens utilize certain organic acids ; the 
reaction is regarded as analogous to bacterial fermentations of acids. 
9. Hydrogen-ion concentration exercises a regulating effect on growth : 
the growth reactions obtained with the species of Eidamia bear a definite 
relation to the relative degree of acid tolerance exhibited by them. 
10. Growth retardation is often correlated with increased molecular 
concentration (acids): E. catemdata and E. viridescens differ in their response 
to altered molecular concentration. 
11. The coloration ultimately appearing in certain cultures of E. viri¬ 
descens and E. catemdata containing gallic acid and protein is due to the 
oxidation of the acid owing to the presence of free alkali. 
12. The principle causing spore coloration in E. catemdata and 
E. viridescens is insoluble in ether, chloroform, and the usual solvents. 
13. E. viridescens is parasitic 011 apples at i° C., and at ordinary labora¬ 
tory temperatures E. catemdata and E. acremonioides are saprophytic, 
V. Summary. 
The salient morphological features of three species of Eidamia , includ¬ 
ing two which are apparently new to science, are described. The reactions 
which these species exhibit when grown in various media, including sugars, 
soluble pectin, protein, organic acids, and various other substances, are com¬ 
pared and contrasted. The growth-limits of the species in relation to 
hydrogen-ion concentration are approximately determined. 
The authors are greatly indebted to Professor V. H. Blackman for his 
very kind advice and criticisms, and to Mr. A. B. Manning for help in matters 
relating to physical chemistry ; also to Mr. J. Ramsbottom of the British 
Museum (Natural History) for assistance in connexion with the systematics 
of Eidamia and for the specific descriptions. 
This work was undertaken in connexion with investigations now being 
carried out for the Food Investigation Board of the Department of Scienti¬ 
fic and Industrial Research. 
F f 2 
