DopGE : METHODS OF CULTURE OF ASCOBOLACEAE 161 
may reach a temperature of 50° C. in 30 minutes. This moder- 
ate rise in temperature has evidently a very stimulating effect 
on the spores, though the per cent of germination so achieved 
is not high. 
In the following table (TABLE III) I have brought together a 
summary of the results of my experiments on the effect of heat on 
the germination of the spores of Ascobolus carbonarius. 
The table shows that in the one hundred and twelve trials over 
go per cent of the spores germinated when heated in an oven for 
periods of from 15 to 40 minutes, the temperatures running up to 
but not exceeding 80°C. The highest per cent of germination 
was obtained by heating the oven up to from 70°-75° C. within 
the time limits specified. It is clear that the spores of this species 
very seldom germinate under cultural conditions unless heated to 
at least 50° C. for several minutes. Germination takes place 
equally well in such liquid media as tap water, decoctions of 
carbonaceous earth, decoctions of heated soil, and in dung decoc- 
tions; no difference in the percentage of germination is apparent 
when an agar medium made up with any of the decoctions just 
mentioned is employed, or when a peptone glucose agar or a 
malt agar is used. The percentage of germination is 90 per cent 
or over in all cases where the spores have been heated to 60°-75° 
C. for a few minutes. 
To obtain a more definite idea of the minimum, optimum, and 
maximum temperatures for the germination of spores of Ascobolus 
carbonarius two series of experiments were made. (a) About twenty 
Spores were placed in each of eleven test tubes half filled with a 
decoction of heated soil. A thermometer was used to stir the con- 
tents of the tubes while heating them separately in hot water baths. 
Each tube was heated for three minutes after its contents had been 
raised to the desired temperature, and was then cooled quickly by 
Placing it in a cold water bath. After 24 hours the contents of 
the tubes were poured into watch glasses and the per cent of 
germinated spores ascertained by actual count. Observations 
made at the end of three days and again at the end of seven days 
showed that there was no further germination after the first 24 
hours. Tape IV shows the results of this set of experiments. 
(6) In the second series the spores were allowed to remain on 
