19191 



WEBB — SPORE GERMINATION AND H ION CONCENTRATION 



211 



decrease in percentage of germination. Only a compar 

 small amount of termination is obtained in the cul 



ture testing P H 7.4 and no 



evident 



P H 8.8. The limiting concentration of hydrogen ions lies be- 

 tween P H 7.4 and 8.8 on the alkaline side, and below P H 2.8 on 



the acid side. 



Examination of the same series after an incubation of 26 and 



38 hours, respectively, shows that germination has increased in 



all the cultures and that there have been several slight changes 



in the curve of germination. A slight maximum is noticed on 



■ 



the alkaline side 



H 



7 



ermination is obtained 



and a relatively low percentage of 

 P H 8.8, which at 16 hours was the 



m 



A series incubated at 27° C. for 16 hours gives a gem 

 germination very similar to that incubated at 22° C 

 ception of several slight shifts. A 

 obtained at P H 3.1, as before, but 

 l the alkaline side shifts toward neui 



maximum of germination 



H 



there is total inhibition of germination, as compared 



H 



7.4 

 9.6 



in the first series, 

 from P H 3.1 there 

 tion to culture P t 

 a relatively small 



With decrease in hydrogen 

 i a general decrease in nerct 



6.2 where a minimum is reached, followed by 

 rise at P„ 7.0. Upon incubating the series for 

 10 additional hours, the same relations of germination are ob- 

 tained. On account of the luxuriant mycelial growth, only two 

 readings were possible with this 



Incubation at 31 

 incubated at 27° C 



mum 



C. gives slightly different results from those 

 At the time of the first reading the maxi- 



and there is no evidence of stimula- 

 tion of germination in the neutral or slightly alkaline cultures. 

 On the other hand, germination decreases with decrease in H ion 

 concentration from P H 3.1 to 7.0, the limiting concentration 



ng maximum germi- 

 ius making the max- 



be 



7.4. 



read 



H 



nation on the acid side shifts to I 

 imum germination at each temperature occur at P H 3.1; and 

 the remaining figures confirm the results of the previous exam- 

 ination. 



These relations are shown graphically in the curves of fig. 1 



