1906] BROOKS—TEMPERATURE AND TOXIC ACTION 373 
might have been for this reason enough greater than at lower tem- 
peratures to cause an appreciable change in the results, and the 
series was repeated with the hygroscopic conditions more nearly uni- 
form. Charts 12a and 11 give the results obtained from the first 
series, while 11 and 126 show the results of the last series. In the 
first set of experiments the fungus was allowed to grow two weeks, in 
the last but one week; in the former the cultures for the various tem- 
peratures were started at different times, in the latter all were started 
_ on the same day and the spores used were from one stock culture. 
In charts 11-12 the abscissae indicate temperatures as before, 
but.the ordinates express percentages of dry weight instead of per- 
centages of germination, The effect of temperature on the controls 
is shown in chart 11. In this chart the curves were determined by 
taking the greatest dry weight as 100 and estimating what per cent. 
of this the weights secured at other temperatures were. In charts 
12a and 12b these same controls are represented by the ordinates 
marked too, In plotting the curves of these two charts, the weight of 
fungus secured in a given toxic solution at a particular temperature 
was compared in each case with the weight obtained in the control 
at the same temperature. The results thus obtained are expressed 
by the ordinates as mentioned above. 
It will be seen that in most instances the curves in the two charts 
are in close agreement. Where this is not true, as in the case of the 
controls, the results obtained in the last series should be considered 
the more reliable for the reason previously given. Taking total 
growth as a standard, the injurious effects of the toxic agent have 
decreased with rise of temperature. This decrease is rather to be 
considered as the result of approaching the optimum for the fungus 
than as a mere temperature effect. The effects produced by the 
three chemicals were widely different. The injury resulting in the 
CuSO, solutions was not so great, comparatively, at 15° as at 20°. 
This was true of neither of the acids, Sulfuric acid checked the 
Srowth at the lower temperatures, but in no case served as a strong 
stimulating agent. Nitric acid gave similar injurious effects, but at 
the higher temperatures served as a remarkable stimulus. It should 
be remembered that a similar rise at 25° and 30° was obtained in 
the cell culture curves for HNO,. 
