[Vor. 8 
328 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
Brooks ('06) found that the deleterious action of CuSO,, 
HNO,, and H,SO, in beet decoction medium upon the germina- 
tion and development of certain fungous spores was least at a 
provisional optimum temperature and that it inereased very 
rapidly with rise in temperature above such an optimum. The 
effects of the three chemicals, however, were very different, and 
spores inhibited by cold were not greatly injured when exposed 
to harmful agents. 
Temperature variations such as were employed in the experi- 
ments here reported exert little or no influence upon the curves 
Ano 
beso eee 
g 
E 4 
3 pe 
È éo Dea M 
$ V Pd N 
xil \ 
* SEE: \ ZAN 
P ff A —^ x 
H Hy \ liga E 
E RT i 
» Kk, as Eme 
^t 2 J 4 s 6 7 o ? ^ 
Fig. 30. Fusarium sp. in M/5 mannite solution 
of germination, but it must be remembered that the temperature 
range was relatively narrow. This aspect of the problem will 
be considered later. 
The effect of the hydrogen-ion concentration of the medium 
as influenced by certain types of nutrition, or the chemical 
composition of the nutrient medium, is shown by the results 
presented in this paper to be of extreme importance. Inasmuch 
as a detailed consideration has been devoted to these points for 
the individual fungi, it is necessary to mention only a few of the 
striking features. The results with the various media are 
comparable, yet it is difficult to make general statements that 
would be applicable in all cases. 
