Physiology of the Genus Eidamia . 425 
After the appearance of colour the solution when tested with litmus paper 
proved to be alkaline. 
The more detailed results are as follows: 
E. viridescens. 
Seventh day. No. 2, liquid olive green with suggestion of reddish- 
brown, alkaline, ammonia present. No. 1, liquid without colour change, 
acid. Nos. 3 and 4, little growth, liquid without colour change, acid. 
Tenth day. No. 1, liquid port wine colour, alkaline, ammonia present. 
Nos. 3 and 4, no noteworthy change. 
Thirteenth day. No. 1, liquid dark olive green. Nos. 3 and 4, no 
noteworthy change. 
E. catenulata. 
Seventh day. No. 2, liquid without colour change, acid. No. 1, liquid 
slightly darker in colour, slight alkalinity, ammonia not detected. Nos. 3 
and 4, little growth, liquid without colour change, acid. 
Tenth day. No. 1, further darkening in colour to light brown, alkaline, 
ammonia present. Nos. 2, 3,4, no noteworthy change. 
Fourteenth day. Nos. 1 and 2, solutions port wine colour. Nos. 3 
and 4, no noteworthy change. 
Controls. Liquid unchanged. 
H. General CoJiclusions on Grozvth in Relation to Acids. 
Since the behaviour of fungi in special relation to acids needs more 
detailed investigation than this subject has received hitherto, it is not 
advisable to enter into a discussion of all the factors influencing the growth 
of the species of Eidamia in acids. The present object will be better 
attained by expressing in summarized form the results which appear to 
have a general bearing on fungal work of this nature. 
1. Both E. catemdata and E. viridescens are capable of utilizing certain 
organic acids ; the power of utilization appears to be increased when the 
medium contains other sources of nutriment. 
2. These species, unlike Penicilliinn glaucum , do not markedly utilize 
one only of the two stereo-isomers present in racemic acid. 
3. In a general way hydrogen-ion concentration exercises a regulating 
influence on growth, the degree of its influence varying with the nature of 
the constituents of the medium employed. 
4. Growth in any medium containing acid and compounds of nitrogen 
may be progressively affected by three factors: 
{a) utilization of acid ; 
(b) neutralization of acid through evolution of ammonia ; 
(e) acid production through fermentation of sugar. 
Where the general trend is towards alkalinity, both the molecular con- 
