2 7 2 Brown . — On the Germination and Growth of 
cinerea at 15 0 and 5 0 on apple gelatine in air, 10 per cent, and 20 per cent. 
C 0 2 . All the cultures compared were started on the same day on the 
same medium, as was the invariable practice throughout this work. As 
the curves of growth at the two temperatures are drawn to different scale, 
the relative amount of retardation produced by the C 0 2 treatment is not 
obvious at a glance, but an idea of its magnitude may be obtained by 
comparing the amounts of growth in the C 0 2 cultures at times when the 
air cultures in the two cases have reached the same size. Thus if we read 
Fig. 2. Growth of Botrytis cinerea on apple gelatine at 5 0 . 
off from the graphs the amount of growth in 10 per cent, and 20 per cent. 
C 0 2 corresponding to a diameter of 8 cm. in the air cultures we get the 
following figures : 
Air. io°/ 0 C 0 2 . 2 0 °/ 0 C 0 2 . 
At 15 0 8.0 (100) 5.5 (69) 3.0 (37.5) 
At 5 0 8.0 (100) 4-3 (5 4 1 1. 1 (14) 
The figures in brackets represent the relative amount of growth, that 
in air being taken as 100 in each case. 
It will be observed that at the times when the air cultures at the two 
temperatures have reached the same diameter the corresponding amount of 
growth in the C 0 2 atmospheres is considerably less at 5 0 than at 15 0 . This 
result may be expressed generally in the following terms : The relative 
retarding effect of a given concentration of carbon dioxide is greater at a low 
than at a higher temperature. 
Strictly speaking, a correction should be made in the above curves 
for the diameter of the original inoculum, which in the case of Botrytis was 
