EXCRETION OF CYTASE BY PENICILLIUM PINOPHILUM. 



31 



the sections into the substratum, and at a temperature of 30° C. 



the clarifying action is usually noticeable within 72 hours. 



DEMONSTRATION OF ACTION OF CYTASE. 



Figure 2 shows the relative effect of agar charged with cytase taken 

 at different depths from the growing fungous layer. From a culture 

 of Penicillium pinophilum Hedg., 1 28 days old, four sections, each ap- 

 proximately one-eighth of an inch in thickness, were cut from the 

 relative positions indicated by the brackets numbered 1, 2, 3, and 4 

 in figure 1. It should be noted that section No. -1 is entirely below the 



Fig. 2. — Result of the action upon amorphous cellulose of sections ol agar which contain 

 a cytase produced by PcnicilMuni pinophilum. 



cleared zone and contains flocculent callulose apparently identical with 

 that in the sterile tube. These four sections were transferred to a 

 firm layer of cellulose agar in a Petri dish and held at 30° C. for five 

 days. They were then removed, carefully examined, and found to be 

 sterile; yet, as shown in figure 2, the amorphous cellulose held in sus- 

 pension immediately beneath section No. 1 was more or less com- 

 pletely dissolved. It was dissolved to a less degree under section No. 

 2, but slightly under section No. 3, and was unaffected under section 

 No. 4. 



It is obvious from this demonstration that true cytases, slowly 

 diffusible through agar, may be isolated in appreciable quantities. 



1 Identified by Dr. Charles A. Thorn, Mycologist in Charge of Cheese Investigations, 

 Bureau of Animal Industry, U. S. Department of Agriculture. 

 [Cir. 118.] 



o 



