409 
Physiology of the Genus Eidamia. 
E. catenulata and E. viridescens , were employed. The solutions of HCl 
and HCl potato extract were made up in 250 c.c. flasks containing each 100 
c.c. of liquid. The HCl potato extract agar was used for plate 
cultures, and growth measurements in terms of the diameter of the colony 
were made at regular intervals. The more important results are given in 
tabular form below : 
Growth m media containing HCl of different initial hydrogen- 
ion concentrations at 20 ° C. 
Medium. 
pH. 
E . catenulata. 
E. viridescens. 
N 
JO 
HCl sol. 
1.03 
nil 
nil 
N 
HCl P.E. sol. 
1.16 
several small colonies 
nil 
N 
HCl P.E. agar 
1.23 
colony 5 mm. 
St 
nil 
TO 
N 
100 
HCl sol. 
2.0 
numerous colonies 
(14 days) 
very slight growth 
(3 da ys) 
numerous colonies 
(14 days) 
N 
1000 
N 
100 
HCl sol. 
3 -o 
numerous colonies 
(14 days) 
some growth 
HCl P.E. agar 
4- x 5 
colony 1-5 cm. 
colony 6-2 cm. 
N 
100 
HCl P.E. sol. 
4-35 
much growth, 
larger colonies 
much growth 
Distilled water 
5-8 
nil 
nil 
JN 
IOOO 
HCl P.E. agar 
64 
colony 0-85 cm. 
colony 3 cm. 
N 
1000 
HCl P.E. sol. 
CO 
00 
one colony 
(similar to P.E. 
control) 
much growth 
N.B. The data given are those after 3 days’ growth unless stated otherwise. 
The following points are evident : 
1. The limit for E. catenulata (in N/10 HCl P.E. solution) is pH 1-16 
approximately. 
2. The limit for E. viridescens (in N/100 HCl) is approximately pH 2. 
It will be noted that growth diminishes as the neutral point is approached 
with both species ( see growth in solutions initially pH 4-15 and pH 6-4 
respectively). 
In the case of E. acremonioides no growth was obtained in nutrient 
media containing more than one per cent, concentration of malic or tartaric 
acid : the hydrogen-ion concentration of these media would be less than that 
indicated by pH 3. 
In order to obtain growth limits on the alkaline ¥ side a boric acid buffer 
solution was employed. The solutions used were prepared as follows : 
A. Buffer solution only, in flasks. 
(a) 50 c.c. H3BO3, KC 1 (12-4048 grm. H 3 B 0 3 + 14-912 grm. KC 1 to 
