Fungi at various Temperatures, &c. 
271 
of growth too frequently, as each measurement involved a certain amount 
of disturbance of the experimental conditions intended. On the other hand, 
if the interval between successive measurements was too long, the accumu- 
lation of carbon dioxide in the containers tended to upset the experimental 
conditions aimed at. A compromise had therefore to be effected. From 
numerous analyses a fairly good idea of the rate at which carbon dioxide 
was formed in the containers was obtained, and from that it was possible 
to arrange to make each set of measurements at a time when the C 0 2 
content of each vessel did not exceed that originally intended by more than 
a certain percentage ; in practice a limit of 2 per cent, was imposed. In the 
early stages of each experiment the deviation from the theoretical value at 
each time of measurement was 
much less than this limit, but 
towards the end of the ex- 
periment this limiting deviation 
was frequently reached. Thus 
in referring to growth in air, in 
10 per cent, and in 20 per cent. 
C 0 2 , what is really meant is 
growth in atmospheres con- 
taining 0-2 per cent., 10-12 per 
cent., 20-22 per cent. C 0 2 re- 
spectively. The effect on growth 
produced by 2 per cent. C 0 2 is 
small, and in any case what effect 
there is would only tend to 
make the results a little less 
pronounced than otherwise, see- 
ing that the increase in C 0 2 
content due to respiration was always somewhat more 
the original C 0 2 concentration in the container. 
All the fungi listed earlier in the paper were examined and the usual 
variety of media — potato agar, potato-, apple-, plum-, prune-gelatine, &c. — 
were employed. A series of experiments was run comparing the rates of 
growth in air, 10 per cent, and 20 per cent. C 0 2 at 1 5 0 , 20°, and 25 0 ; 
a further series at io°, 15° and 20° ; and finally a more thorough comparison 
made of the rates of growth in the various atmospheres at 5 0 and 15 0 . 
A comparison was also made of the rate of growth of Botrytis cinerea. 
Monilia cinerea , Alternaria grossulariae, and Fusarium sp. in the various 
atmospheres at ordinary laboratory temperature (15-18°) with that at the 
ordinary cold storage temperature of 3 0 . 
The general nature of the result will be seen by a study of Figs. 1 
and 2, which represent the growth in diameter of colonies of Botrytis 
Fig. 1. 
Growth of Botrytis cinerea on apple 
gelatine at 15 0 . 
*apid the lower 
