(Vou. 8 
16 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
differentiations caused by such environmental conditions might 
remain as fixed physiological characters of fungi is an open 
question. 
In the experiments which I have performed I had not in mind 
being able to distinguish species or races in Rhizoctonia by such 
physiological characteristics as variation in enzymic activity. 
Nevertheless, the use of carefully arranged experiments of this 
type with synthetic culture media may afford additional oppor- 
tunities for the identification of strains. 
METHOD OF PREPARING ENZYME 
The mycelium or felt obtained from a liquid culture was 
washed several times with distilled water. It was then dried, 
either by electric fan or heat, and finally transferred to a desicca- 
tor. After two days it was accurately weighed and a certain 
amount of the mycelium crushed and added to a definite volume 
of distilled water. After being incubated for several hours at 
35-40? C., the solution was filtered and a fixed amount of this 
filtrate employed with the substratum to be studied. The mixed 
solution was incubated at about 30° C. As an antiseptic 2 per 
cent toluol was used. 
With regard to the proper stage of growth of the mycelium 
for investigation, Malfitano, in his study of proteolytic enzymes 
stated that the enzymes showed their greatest activity when the 
mycelium had reached its maximum growth. Zeller (’16), in 
his study of Lenzites saepiaria, found the greater activity in the 
mycelium in the case of all enzymes except oxidase, which was 
greater in the sporophore. Young ('18) also observed that inu- 
lase was present in the fungous mycelium in greater amount in 
the period of sporulation of the fungus and rapidly disappeared 
after that time. 
In my work a qualitative study of the diastase activity in 
mycelial and sclerotial stages was made. As might be expected, 
the greatest activity was synchronized with maximum growth. 
Therefore, in the present investigation it was decided that all 
the material should be prepared as described as soon as the 
cultures showed the first sclerotia formation. In general, when 
the strains are cultivated in potato decoction and kept at 23- 
25° C., the sclerotia formation of Pl and H was 1 or 2 days 
