214 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



{Vol. 6 



Fig. 2. Pcnicillium cyclopium. Graphic representation of the relation of ger- 

 mination to H ion concentration. 



impossible to make a third reading. These relations are shown 

 graphically in fig. 2. 



An acid reaction decidedly favors spore germination of Botrytis 

 cinerea, as seen by referring to table in. 



BOTRYTIS CINEREA. 



M/5 MANNITE 



TABLE III 



AVERAGE PERCENTAGES OF SPORE 

 AT DIFFERENT TEMPERATURES AND 

 HYDROGEN ION CONCENTRATIONS 



GERMINATION 

 AT VARIOUS 



IN 



Temp. 



Hrs. 



Hydrogen ion concentration, P H 



2.8 



3.1 



4.4 



5.0 



6.2 



7.0 



7.4 



8.s 



9.(i 





» 



10.0+ 



22° C. 



6 

 21 



27° C. 



70.0 

 77.1 





6 

 21 



42.0 

 92.4 



86.6 

 90.2 



32.2 

 66.4 



63.4 

 72.9 



50.0 

 61.2 



52.6 

 62.6 



22.3 

 34.9 



48 . :: 



57 . 8 



15.3 

 30.1 





22.3 

 46.0 



0.0 

 0.0 



o.O 



0.0 



0.0 

 0.0 



0.0 

 0.0 



0.0 

 0.0 



0.0 

 0.0 



0.0 

 0.0 



0.0 

 0.0 



0.0 

 0.0 



Incubated at 22° C. no germination is obtained at P H 7.4; little 

 germination is obtained at P„7.0; and, with increasing hydrogen 

 ion concentration, the germination quantities increase until a 



reached 



culture with P„3.1. With further 



crease of hydrogen ion concentration, there is a diminution 



percentage of germination, 

 bation neriod of 21 hours ai 



obtained 



