ACID FERMENTATIONS. 357 



from 1.5 grms. of grape sugar in presence of added chalk, at 



i5-2oC. : 



After ii days 0.282 grin. After 72 days 1.340 grms. 



1 6 ., 0.570 100 1.642 



M 27 0.650] 120 1.615 



4<5 ,, 1. 122 247 1.730 



In the absence of added chalk, the amounts precipitated from the 

 same nutrient solution were only : 



After 9 days 0.005 grm. After 66 days 0.298 grin. 

 ,, 16 ,, 0.070 ,, ,, 78 ,, 0:130 



,, 23 ,, 0.170 ,, 97 ,, 0.103 



46 0.255 > 120 0018 



54 ,, 0.248 ,, ,, 175 ,, 0.014 



At higher temperatures (34-35 C.), under otherwise equal 

 conditions, only traces of oxalate were formed, viz. ; 



Af er 4 days o.ooo grin. After 32 days trace 



8 ,, 0.008 ,, ,, 42 ,, 



,, 15 ,, 0.028 ,, 68 0.068 grin. 

 ,, 1 8 ,, o.ooo ,, 



On the other hand, at 7-9 C., without chalk, 0.624-0.820 grm. 

 was found after about seven months ; and with chalk, even at a 

 temperature of 34-35 0., there was obtained from the same 

 amount of sugar (1.5 grms.), 1.133 grms. of calcium oxalate at the 

 end of forty-six days, and 1.340 grms. after seventy-two days. 



In order to withdraw the acid from the further action of this 

 physiologically interesting fungus by fixation, it is not even 

 necessary to convert it into an insoluble salt, the same effect 

 being produced by the aid of soluble salts, such as alkali phos- 

 phates of alkaline reaction, and even neutral alkali phosphates, 

 the latter being transformed into acid oxalates. Apparently the 

 appearance of alkali acid phosphates in phanerogams (Oxalis, &c.) 

 is based on this circumstance. Conversely, it is interesting to 

 find that Penicillium glaucum decomposes both free acids and 

 alkali oxalates much more readily than Aspergillus does, and, 

 therefore, if for no other reason, cannot be a generator of acidity 

 to any extent. 



Although, in general, experiments of this kind with Asp. niger 

 proceed with the certainty of a chemical test, variations are not 

 unknown in individual cases. The isolated instances in which 

 WEHMER (XVII.) and EMMERLING (VI.) found no acidification 

 must probably be allocated to this category. Other factors may, 

 perhaps, have contributed, since, according to a previous discovery 

 by WEHMER (XXVIII.), the addition of even a trace of iron 

 salts to cultures grown in the light can favour the redecomposition 

 of the acid. References to the formation of oxalic acid by Asp. 

 niger are also found in certain recent investigations, such as in 



