1921] 
MATSUMOTO—SPECIALIZATION IN RHIZOCTONIA 23 
this experiment it will be safe to assume that the diastatic effi- 
ciency manifested by original strains may be regarded as a 
permanent and fixed characteristic, but the enzymatic activity 
may be modified by a transfer to the host plants, while after 
continual culture in the laboratory it was rather constant on 
uniform culture media. 
With respect to the presence of invertase in these fungi, the 
following experiments were performed in the same way as de- 
cribed above but using 2 per cent cane sugar instead of starch. 
TABLE X 
INVERTASE ACTIVITY p gor STRAINS s X INCUBATION PERIOD 
1 HOURS AND 2 
Con- | Per. 
P1 P4 wi B1 H B3 trol | (hrs.) 
Reducing sugar (mgs.) 5.39| 18.45| 14.40| 12.80| 4.91| 5.88| Negl.| 21 
Invertase activity 29.91/100.00| 78.05| 69.38| 26.61| 31.87| 0 21 
Reducing sugar (mgs.) 7.35| 85.38| 38.45| 91.90} 7.35| 7.35| Negl.| 48 
Invertase activity 8.00| 92.90| 41.84/100.00| 8.00| 8.00| O0 48 
This study was repeated several times, using several mycelial 
extracts obtained from various culture media. With the ex- 
ception of a slight modification, all the experiments show the 
same tendency as appears above. All strains possess the power 
of producing hexoses from cane sugar in excess of the food re- 
quirements. Invertase activity of P4, P7, and B1 is relatively 
high, while that of P1, H, and B3 is poor. 
A comparative study was also made of the invertase activity 
of the reisolated strains of P1 and B1, with the result that these 
gave respectively 4.38 and 6.11 mgs. reducing sugar as compared 
with 4.12 mgs. in the original P1. 
Maltose and Lactose.—To the stock culture solution previously 
described 2 per cent maltose and lactose were added, 40 cc. of 
Sach solution then placed in Erlenmeyer flasks and inoculated. 
Table x1 gives the results after 3 weeks. 
As shown by the table, the nutritive value of maltose is about 
the same as that of dextrose, while that of lactose seems to be 
much less than that of the other sugars. 
