[Vox. 8 
18 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
precipitated by steam. The result obtained after an incubation 
of 3 weeks is shown in the following table: 
TABLE IV 
DRY WEIGHT OF MYCELIUM OF 6 STRAINS OF RHIZOCTONIA 
Strains of Rhizoctonia (gms.) 
Medium | p, 
contains 
Pl P4 P7 B1 H B3 
Glucose 0.140 0.145 0.127 0.010 0.147 0.005 
Starch 0.165 0.195 0.090 0.010 0.160 0.005 
7.0 
Sucrose 7.0 0.185 0.180 0.145 0.010 0.181 0.005 
7.0 
Control* 7.2 Negl. Negl. Negl. Negl. Negl. Negl. 
* No carbohydrate. 
At the beginning the mycelial growth of P4 in the sucrose 
and starch solutions was rather less in quantity than the glucose 
solution. Gradually, however, the development became more 
vigorous, and the final results, as shown above, were better than 
in the latter. The same was true with Pl and H. This relation 
held true with P7 in the case of sucrose media, but on the media 
containing starch this strain showed the poorest growth. Growth 
of B1 and B3 is very scant on any of the media studied, although 
B1 can grow fairly well on any of the solid media studied. 
The course of development just mentioned makes plausible 
the supposition that the cane sugar and starch were at first 
slowly converted by these fungi, but inasmuch as the gradual 
conversion may after a time keep pace with the requirements 
(where suitable enzymes are secreted), this may be regarded as 
a favorable factor. The capacities of these forms to produce 
the necessary hydrolyzing enzymes became a problem of in- 
terest in this work. 
Growth on potato decoction and starch solution.— Three hundred 
grams of potatoes were sliced as thin as possible, cooked in 1000 
ec. water for 1 hour at about 100? C., then strained through 
cloth, and 50 ec. of the decoction used in each Erlenmeyer flask. 
The flasks were autoclaved for 15 minutes at 15 pounds pressure, 
after which they were inoculated with the various strains. 
Duplicate flasks inoculated were kept as controls. 
