4 
It will be noticed that proteolytic activity is present in both 
extracts in both fungi, but it is extremely marked in the medium 
in the case of Aspergillus niger. 
This indicates that the fungus during its growth excretes 
into the medium, in which it is situated, a proteolytic enzyme, 
which brings the complex proteids into a fit state for assimilation 
by the organisms. 
In experimenting with Bacillus prodigiosus, the bacteria 
were separated from the medium by means of a centrifugal 
machine, and ground in a mortar with solid carbon dioxide and 
ether. Tenc.c. of distilled water were then added, and 3 c.c. of the 
mixture put into each of three flasks with ‘2 gm. protein, and the 
experiment carried out as in the other cases. The medium was 
filtered through a Chamberland filter in order to get rid of the 
remaining bacteria, and then used for the digestions in the usual 
manner. 
