1923] 



CAMP — CITRIC ACID AS A SOURCE OP CARBON 



247 



procedure of Webb ('21) and the solution just described. Solu- 

 tions with a P H of 3.0, 2.7, 2.5, and 2.2 were tried with checks of 

 sterilized, distilled water. One slide with 2 rings was used for 

 the control and 3 slides with 2 rings each for the solution. The 

 spores were mixed with a glass rod in a few drops of the solution 

 on a clean slide until a suspension of proper strength had been 

 attained and then were transferred to the cover slip. All slides 

 were incubated at 25° C. Where possible 3 counts were made 

 of each drop and the results averaged ; in some cases the germina- 

 tion was so heavy and rapid that it could only be estimated. A 

 few notes were made concerning the nature of the germination 

 where it seemed to be especially significant. The results of these 

 tests are given in table in. 



TABLE III 



PERCENTAGE OF GERMINATION AT P H 3.0, 2.7, AND 2.5 



Cul- 

 ture 



Period 

 (hours) 



H-ion concentration 



3.0 



2.7 



2.5 



Check 



14 

 7 

 

 9 

 2 

 2 

 3 

 3 



24 

 24 

 24 



48 

 24 



36 

 24 



48 



24, 25, 35 



None 



90 (av.) 



44,75 





87, 1, 25 



44, 36, 25 



None 

 57, 40, 95 



None 



50* 

 Drops overgrown 



67,77 

 Few 

 100 



90, 50, 75 

 Occasional 

 25, 50, 25 



Occasional 



0,71 



23 

 25 



* 50 per cent where spores were bunched, lower elsewhere. 



Culture 9 gave such strong germination that it was difficult 

 to estimate the percentage, the germination being much better 

 where the spores were grouped together. At P H 2.5 about 50 per 

 cent of the bunched spores had germinated in 24 hours, while 



practically none of the isolated spores had germinated, 

 may have been due to the collective action of the bunched 



This 



the Ph of the surroundin 



The results were extremely 



ith the Penicillium 



almost 100 



One circle might 



germination and the other 



the same slide little or no germination. For P 



H 



tube method 





