[Vor. 8 
394 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
other factors. A. niger produces no changes in solutions of 
mannite or in Czapek's solution, but does cause certain shifts 
towards neutrality in the alkaline cultures of the beet decoction. 
This organism produces in the presence of sugar an extremely 
large quantity of acid during growth, and it is not surprising 
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vu a p Pr 
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Fig. 37. Colletotrichum Gossypii in Czapek's full nutrient solution. 
that such reversions do occur in beet decoction, a solution poorly 
buffered and containing a high percentage of sugar. B. cinerea 
produces no changes in reaction while germinating in solutions 
of mannite, Czapek's solution, “water H,PO, or NaOH" and 
“water HCl or KOH." However, it does produce changes in 
the beet decoction solutions similar to, but in less degree than 
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2 
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ki , 
È p EN / 
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^s ^ p^ s m M^ 
&. so EA oca rl ee ae 
* A 
E p 2r 
5 / 2 3 4 5 6 7 ð ? ^o 
Fig. 38. Colletotrichum Gossypii in sugar beet decoction. 
A. niger. The fact that no change whatsoever in reaction occurs 
with water lacking buffer effect and that relatively slight changes 
occur in beet decoction, a medium also poorly buffered, would 
seem to eliminate the possibility of explaining germination under 
conditions of active alkalinity entirely on the basis of change in 
reaction during this process. Fusarium sp. causes no changes 
in reaction of mannite and ''water HPO, or NaOH" during 
