[Vor. 4, 1917] 
288 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
nutrition to fruiting are worthy of consideration. Asper- 
gillus fruits so readily that experiments with this form might 
seem to be of little value, yet knowledge concerning factors 
effecting an inhibition of fruiting is likewise important. 
Richards! and others have shown that associated with the in- 
creased growth resulting from the addition of ZnSO, and cer- 
tain other metallic salts is the depression of fruiting. Num- 
erous observations of this general nature might be collected. 
In this paper it is not intended to enter upon a general dis- 
cussion of nutrients affecting spore production. It has 
seemed, however, that the influence upon spore formation of 
such variations in nutrient conditions as have been studied 
are worthy of record, and it is intended to pursue further this 
line of inquiry in subsequent work, for which fungi better 
adapted to the purpose have been selected. 
In our previous paper it was pointed out that even a crude 
study by the colorimetrie method of the hydrogen ion concen- 
tration of the various decoctions employed leads to the conclu- 
sion that the titration of such media and the standardization 
of these on the basis of Fuller's scale are unsatisfaetory. No 
adequate study of this point has been undertaken, and such 
determinations as were made served merely as a rough check 
on the conditions involved in our work. The values of P,, 
in the various natural decoctions employed were approxi- 
mately as follows: apple, 4.3; mangold, 4.5; carrot, 5.3; and 
salmon, 6. It is interesting to note that although Asper- 
gulus grows well in the natural mangold decoction with 
P,,—4.5, when brought to Р,, = 6, there is produced a heavier 
mat. Аз in the earlier experiments reported, the hydrogen 
ion concentrations of the solutions in which Aspergillus have 
grown are shifted toward the acid side, while in the contrary 
direction in the cultures which have supported Gloeosporium. 
1 Richards, H. M. Die Beeinflussung des м einiger Pilze durch 
chemische Reize. Jahrb. f. wiss. Bot. 30: 665—688. 1897. 
