[Vol. 6 



220 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



quantities at or about neutral is followed by a general decline. 

 The limiting concentration on the alkaline side is about P„10.0 + , 

 thus presenting a range of germination greater than that of 

 Asveraillus niaer. 



From my 



be regarded 



very sensitive to an alkaline reaction in mannite solution or else 

 as manifesting a certain dependence upon the stimulating effects 

 of hydrogen ion concentration under such conditions. Not only 

 is germination inhibited at P„ 7.0 -7.4, but the maximum, reached 

 at P H 3.1-2.8, is equivalent to about N/1000 acid. The range of 

 germination in this case is small. 



Lenzites saepiaria, like Botrytis cinerea, proved very sensitive 

 to an alkaline reaction, and, while the limiting concentration of 

 the former on the acid side is somewhat lower than the latter, 

 the two fungi are similar in behavior. Meacham ('18) ob- 

 tained inhibition of growth of Lenzites saepiaria at about P H 1.7 

 in synthetic and malt-extract, and it is of interest to note that 

 he frequently obtained a maximum of growth at about P H 3.0, 

 which approaches very closely the hydrogen ion concentration 

 of M/5 mannite which affords maximum germination, as re- 

 ported in this paper. 



Of the forms studied, Fusarium sp. is the only one that re- 

 sponded favorably to an alkaline medium. Moreover, this 



form exhibits about the widest 

 behavior was variable and discord 



yet the 



Conclusions 



Under the conditions described and as far as the experiments 

 have gone, the following conclusions may be drawn: 



(1) In a culture solution consisting of M/5 mannite, phos- 

 phoric acid, and sodium hydroxide, successively increasing con- 

 centrations of hydrogen ions from neutral or approximately 

 neutral to P H 3.1-2.8 favorably influence germination of the 

 spores of Aspergillus niger, Penicillium cyclopium, Botrytis 

 cinerea, Fusarium sp., and Lenzites saepiaria. 



(2) The range of germination and the magnitude of the ger- 

 mination quantities as influenced by hydrogen ion concentration 

 in the solution mentioned depend upon the organism, germina- 



