266 Brown. — On the Germination and Growth of 
again examined, as it was thought conceivable that a diminution of oxygen 
pressure which would not affect the germination of spores might affect the 
rate of growth of a large fungal colony. Experiments were carried out 
to compare the growth of Sphaeropsis colonies in containers in air at 
atmospheric pressure with that of similar colonies maintained in air at 
40 per cent, of the normal pressure. No definite difference could be 
established between the former growing at 20 per cent, oxygen pressure 
and the latter at 8 per cent. It was therefore concluded that, for all the 
purposes of the present investigation, oxygen pressure was a factor of no 
importance within the limits laid down by the practical aspects of the 
problem. As regards the effect of the composition of the atmosphere on 
the germination and growth of fungi, attention was therefore directed solely 
to the carbon dioxide constituent. 
The general nature of the retarding action of carbon dioxide on 
germination having been studied as above described, experiments were now 
set up to determine what concentrations of carbon dioxide were necessary 
to inhibit the germination of fungal spores under various conditions of 
nutrition. Parallel series of germination tests were set up, in the one case 
in water and in the other in a good nutrient. For the latter a turnip 
extract of one-fifth full strength was used. These experiments were carried 
out at laboratory temperature. 
The general type of result will be seen from the following table. The 
various preparations were set up in the usual way in moist containers. 
The table describes the progress which has been made in germination after 
seven days from the start of the experiment. 
Taele IV. 
Spores sown in T.E./5. 
Fungus. 
20 % C0 2 
30 %. 
4° %• 
5° %• 
60 %• 
Botrytis parasitica 
weft 
weft 
strong 
germination 
c- 50% 
germination 
Very occasional 
papilla 
B. cinerea . . . 
11 
” 
good 
germination 
none 
none 
Monilia cinerea 
11 
rare 
germination 
none 
Mu cor sp. ... 
long germ- 
tubes 
short germ- 
tubes 
none 
none 
none 
Rhizopus nigricans 
weft 
weft 
weft 
good 
germination 
rare 
germination 
Penicillium glctucum and Fusarium sp. were the only two fungi which 
were found to germinate strongly in 60 per cent. C 0 2 . 
It must be observed that the time of seven days allowed for germination 
is purely arbitrary, and that though in some cases germination had not 
taken place in this time, it does not follow that some germination would not 
eventually have occurred. 
In all cases it was observed that the carbon dioxide treatment did not 
appear to harm the fungi in any way, for they germinated normally and 
