Apt. 7, 1923 
Temperature Relations of Eleven Species of Rhisopus 31 
INFLUENCE OF TEMPERATURE ON FRUITING. 
It has been repeatedly demonstrated by different investigators that 
the range of temperature at which fungi will sporulate is not coextensive 
with that at which they will grow. It has been proved that the various 
species of Rhizopus often cause considerable damage to vegetables and 
fruits. Although under suitable environmental conditions the causal 
organism can spread from host to host by means of their mycelium, their 
distribution is accomplished largely by means of the spores. It was 
therefore thought that information regarding the effect of temperature 
on sporangia formation, especially at the lower temperatures, might be 
of considerable practical value. The data accumulated during these 
studies are given, together with the data on the effect of temperatures 
on spore germination and growth, in Table I. In all cases those tem¬ 
peratures at which no growth took place and those at which some growth 
was made are listed in the columns headed “absent'' and “present," 
respectively. The results show that fruiting of these fungi takes place 
over a considerable range of temperature. The optimum for some of 
the species is rather sharp and can be easily determined, while in other 
cases it extends over several degrees. Chinensis^ nigricans, and arto- 
carpi, which showed very sharp optimums for spore germination, fruited 
about equally well over a considerable range of temperatures. On the 
other hand, arrhizus, reflexus, and nodosus respond readily to tempera¬ 
ture, both in regard to germination and fruiting. 
Although artocarpi Mongs to the low-temj^rature group, when its 
optimum is considered it stands among the highest-temperature forms 
with respect to its minimum for fruiting. Nigricans and reflexus, two 
low-temperature forms, also have a low minimum for fruiting; whereas 
chinensis, which has the highest optimum and maximum, has about 
the same minimum as the intermediate forms. The group consisting 
of tritici, delemar, arrhizus, oryzae, and nodosus has practically the same 
minimum, optimum, and maximum temperatures for both growth and 
fruiting. Hanzawa (9) found that delemar and nodosus did not fruit 
at 37® to 42® and 38® C., respectively. The maximum for arrhizus 
and chinensis was found by Hanzawa to be 36° and 38° to 42°, respec¬ 
tively. Of the five species just mentioned, tritici and nodosus alone 
formed sporangia at 8® to 10®. Hagem { 8 ) gives 38® as the upper limit 
for nodosus and 36® as the maximum for arrhizus. 
