[Vor. 8 
330 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
Czapek's full nutrient solution generally exhibits germination 
ranges similar to those afforded by the peptone solutions, but 
the eurves of germination in the Czapek differ decidedly from 
those developed in the peptone. Invariably two maxima occur: 
one between Pg 3.0 and 4.0 and the other between Pg 6.0 and 
7.0, and these maxima present more or less definite peaks in the 
curve. It is interesting to note that there is frequently a decided 
decrease of germination quantities at or near Px 5.0. This 
minimum within the favorable range occurs in the culture con- 
taining the normal Czapek full nutrient solution without additions 
of either acid or alkali. 
isos , 
/ 
M 
K 
* 
Rs 2 3 4 5s 6 7 é 9 10 
Fig. 32. Fusarium sp. in Czapek’s full nutrient solution. 
“Water HCl or KOH” allows very wide ranges in germination 
as well as maxima on the acid and alkaline sides of neutrality. 
The spores of Botrytis cinerea and Puccinia graminis germinate 
freely in aqueous solutions with hydrogen-ion concentrations 
which in most of the other culture solutions would have caused 
inhibition of germination. 
Beet decoction, it has been shown, furnishes highest percent- 
ages and the widest range of germination as related to hydrogen- 
ion concentration for all of the spores employed in this investiga- 
tion. Germination occurs freely under conditions of active 
alkalinity in this medium, and hydrogen-ion concentrations 
