1921] 
KARRER—H-ION CONCENTRATION AND AMYLASE ACTION 77 
Analysis of the cultures.—From the following table (table 1) 
it will be seen that the amounts of mycelium of the cultures 
selected for enzyme determinations when expressed on a dry 
weight basis were practically the same at the different H-ion 
concentrations of the nutrient solutions. A small amount of 
growth is also noticeable in these cases. This, however, was to 
TABLE I 
DRY WEIGHT DETERMINATIONS OF ORGANISMS EMPLOYED WITH THE 
INITIAL AND FINAL H-ION CONCENTRATION OF THE 
CULTURE SOLUTION 
Amts. of N/5 HCl and N/20 . 
KOH added in 50 cc. of Ps pae 
nutr. sol. 
Organism Ser. Dry ir^ 
in gms. 
Ce. N/5 HCl | Ce. N/20 KOH| Initial | Final 
I . 0973 0.5 3.0 7.2 
II .0969 SF 4.5 7.8 
Fusarium sp. III . 1061 5.0 7.0 9.0 
IV . 1010 10.0 8.2 9.0 
V 1023 20.0 9.2 9.2 
VI 1069 s 4.5 6.7 
Colletotrichum | VII .0976 5.0 7.0 7.9 
Gossypit VIII . 0982 10.0 8.2 8.4 
IX .0817 rete 20.0 9.2 8.6 
Penicillium x .0897 0.5 3.0 6.0 
italicum XI . 0909 4.5 6.3 
* The average amount of growth produced in one flask containing 50 cc. of cul- 
ture solution. 
be expected since the amount of mycelium produced by these 
organisms is never so luxuriant as that produced by Aspergillus, 
Botrytis, and other fungi. Dox ('10) has also pointed out that 
less growth resulted for the organisms used in his experiments 
in a nutrient solution containing starch than in one containing 
some other carbohydrate. With all the cultures of Fusarium 
sp., growth appeared at the end of about 4 days. The mycelium 
grew on the surface of the solution in a fluffy mat and the spores 
were produced at all H-ion concentrations. At a concentration 
