1906] BROOKS—TEMPERATURE AND TOXIC ACTION 371 
In the former six daily observations were made, in the latter only 
four. Control cultures of spores in beet decoction were kept with 
the toxic cultures at all times. These controls were subjected to the 
various temperatures for the same length of time as the other cultures. 
The per cent. indicated in these charts do not in every instance 
represent the actual germination, but were in all cases obtained by 
dividing the per cent. of germination in the particular culture by that 
in the control at the same temperature. It was found more difficult 
to represent in graphical manner the results obtained from these 
experiments, since the per cent. of germination did not always seem 
to agree with the extent of the injury. The solid lines show the 
germination at the time of the final removal from the given tempera- 
ture. The per cent. of germination at the end of twenty-four hours 
is indicated by the broken lines. These unite with the solid lines 
as they approach the optimum temperatures. Where no broken line 
is given the germination was the same at the end of the first day as 
at the time of removal from the special temperature. The results 
obtained at temperatures at which the controls had not germinated 
were omitted from the curves. This accounts for the fact that a 
number of the curves are not extended to the lower temperatures. 
In all instances the injurious effects were least at the optimum 
for the fungus. This optimum was determined by the germination 
and development in the controls. The harmful effects were shown 
by decreased germination as indicated in the charts and by abnormal 
development. The toxic solutions that gave but partial germination 
at the optimum for the fungus usually gave only abnormal develop- 
ment above and below that optimum. Thus, Botrytis in n/32 HNO, 
gave mycelial development approaching the normal only at 1 5° and 
20°; Penicillium in 2/128 CuSO, gave medium growth at 20° but at 
no other temperature, at 30° the germ tubes seldom became more 
than a few spore diameters in length even after removal to a more 
favorable temperature and many spores swelled without germinating. 
Sterigmatocystis has its optimum above 25° and it is the only fungus 
in which the injurious effects decreased above that temperature. 
Both Mucor and Sterigmatocystis germinated and grew well at 
35°, the other three fungi gave little or no germination at that tem- 
perature, 
