o 1 o l VoL - 6 



^18 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



vlinimum germination occurs in the culture testing P H 7.0, 

 and increases with increase of hydrogen ion concentration to the 

 culture with the value P„ 3.1. At P„ 3.1 the maximum is ob- 

 tained, and with further increase of hydrogen ions there is 

 marked inhibition of germination. The results after 

 of 18 and 30 hours respectively, were very similar. 



Due to limited time, it was possible to run only the one 



ncubation 



series. 



C 



being constructed from the data after a period of 



incubation of 18 hours, the 



the 



run in the experiments reported in this paper, the cultures of each 

 series possessing a hydrogen ion concentration of P„ 7.0 have been 

 regarded as such, it being considered that mannite in doubly 

 distilled water gives a solution with an approximately neutral 

 reaction. Such cultures then contained H and OH ions in 

 equilibrium together with the other ions common to the cultures 

 of the entire series, namely, sodium and phosphorus. 



Discussion 



It is believed that the results here presented are sufficient 

 materially to change the prevailing view as to the relation of 

 spore germination to acid and alkaline media. Among the 

 forms studied, germination is a process which is strikindv snn- 



ported by a relatively high hydrogen ion concentration. In 

 certain forms, secondary maxima may occur at approximately 

 the neutral point, but only in one case among those studied, 

 Fusarium sp., is the primary maximum near the neutral point or 

 on the alkaline side. It is not necessary, of course, to assume 

 that the hydrogen ion concentration most favorable for germina- 

 tion will also prove most favorable for the continued growth 

 and development of the organism. Moreover, that is a problem 

 outside of the present investigation. 



Inasmuch as ordinary nutrient media for pathological and 

 bacteriological work usually exhibit a hydrogen ion concentration 

 approximately neutral or slightly acid, the data obtained from 

 this investigation are further interesting in that they show that 

 successively increasing concentrations of hydrogen ions, from 



