422 Horne and Williamson .— The Morphology and 
media, after final preparation and immediately before inoculation, were as 
follows: 
pH 7*o 
» 3* 8 
» 3*4 
v 3*4 
» 4*2 
Series of plate cultures in duplicate were inoculated with E. catenulata 
and E. viridescens , and kept at 25 0 C. and 20° C. respectively. Growth 
data were recorded in the usual manner. 
In order to show the extent of variation exhibited among members of 
a duplicate series, the actual growth measurements in centimetre diameter 
obtained for E. catenulata are given : 
eta. 
Fig. 22. E . catenulata. Growth on potato extract agar with N/50 solutions of various acids. 
E. catenulata. Growth-rate in media containing N/50 organic acid. 
Acid. 
Series. 
Interval in 
days. 
2 
3 
4 
5 
7 
Citric 
I 
I *45 
2 -5 
2-9 
3*14 
3-5 
II 
i -45 
2.4 
2-8 
— 
3 -o 
Malic 
I 
J, 45 < 
2-6 
3*3 
3-6 
4.2 
II 
i -5 
2-5 
3 -i 
3-45 
4.1 
Tartaric 
I 
1 *55 
2.65 
3*3 
3*35 
3*9 
II 
I, 5 
2.7 
3-4 
3*75 
3-9 
Gallic 
I 
i-6 
2.7 
3*6 
4.6S 1 
6-i 
II 
i *5 
2-6 
3-65 
4.9 
6.6 
Control 
I 
o -75 
i -35 
i-8 
2 -5 
2.8 
II 
0.85 
1.8 
2-5 
2-8 
The general conclusions deduced are as follows : 
I. E. viridescens (Fig. 23) (pH range of the media relatively favourable 
to growth). 
P.E. extract agar control 
and malic acid . 
„ citric acid . 
„ tartaric acid 
gallic acid . 
» 
>> 
>> 
>> 
u 
» 
» 
1 The growth-rate in these cultures was affected by the appearance of additional colonies. 
