188 Dopce: METHODS OF CULTURE OF ASCOBOLACEAE 
It will be of interest to determine whether there are tempera- 
ture optima for spore germination in different groups of fungi, and 
also whether these optima correspond to those for enzyme action 
on fats and other reserve materials found in spores and seeds. 
Melhus (1911), working with the spores of certain Oomycetes, 
has shown that the optimum temperature for the germination of 
spores of Cystopus is below that of the ordinary room and that the 
spores can be germinated abundantly and after being exposed to 
temperatures of 1°-5°C.for 24 hours. Itis not easy to understand, 
why low temperatures should be effective in the case of the Oomy- 
cetes and high temperatures in the Ascobolaceae. The teleuto- 
spores of the rusts can be made to germinate much earlier if artifi- 
cially subjected to low temperatures. Experiments which I have 
tried with Ascobolus, however, seem to indicate that freezing 
temperatures are not generally effective. 
I have been able to germinate spores of several species of the 
Ascobolaceae in an extract of heated soil made slightly acid, and 
have noted a few spores germinating in a film of water on the cover 
of the Petri dish containing the apothecia. My experiments show 
that the acidity or alkalinity of a medium, within certain limits, 
or the amount of nutrient present, are entirely secondary factors 
and of minor importance in connection with spore germination, 
though, of course, these factors are highly important for the growth 
of the mycelium and the production of fruit bodies. As I have | 
described above, the growth of the mycelium and the apothecia 
is apparently accompanied by the formation of certain toxins 
in the medium, which have an inhibitory effect on spore germina- 
tion and on the growth of the mycelium from another region of 
the culture. This might seem to be opposed to Ferguson's obset- 
vation (1902) that the spores of Agaricus can be made to germinal 
by placing small portions of the mycelium in the medium with - 
spores. The statements are, however, not necessarily antagon™ — 
tic. The presence of an actively growing mycelium of the mus? 
room might hinder germination. 
Janczewski (1871) has pointed out the weakness of 4 chat 
acterization of the Ascobolaceae on the basis of the project?” 
of the asci above the surface of the hymenium. He finds that the — 
asci of many species of the Pezizaceae likewise project above the 
