1921] 
MATSUMOTO—SPECIALIZATION IN RHIZOCTONIA 37 
Experiment 2.—Sugar beet decoction was used in the same 
manner, and the result after a growth period of 3 weeks is shown 
in table xxv. 
All the strains, in both experiments, showed an increased 
growth on the acid side. In the first experiment maximum 
growth of all the strains was obtained where the exponent was 
Py 3.9, the highest acidity in the cultures used was Py 2.6, and 
no growth was obtained at Py 2.6 except with B; while, on the 
other hand, as shown in the second experiment, no notable 
differences in growth occurred between the exponent 3.0 and 7.0, 
although at Py 4.4 there is a slight increase in all of the strains. 
TABLE XXV 
THE uio OF H-ION CONCENTRATION ON THE GROWTH OF E ^ ics 
UGAR BEET DECOCTION, THE DECIMAL QUANTIT 
REPRESENT DRY WEIGHT IN GRAMS 
Py 3.0 | Py 4.4 | Pg 5.5 | Pu 7.0 Pa 8.0 Pu 8.6 
Strains 
Scl. | Gr. | Scl. | Gr. | Sel. | Gr. | Sel. | Gr. | Sel. | Gr. | Sel. 
P1 .2001 2 1.225| 3 1]1.225| 2 22015: 2 180] 2 ].155| 2 
P4 .185| 2 /|.190| 4 }.195) 3 190} 3 160) 3 /|.140| 2 
P7 .2000 0 71.1700 0 1.145] 0 Ne 105 O 1.090 0 
Bl .210 2 1.225. 8 |.J25 2 220 2 200; 2 |.190) 1 
H :220]* 2 12250) 8 T 280 0T 2 290] 2 10001 2 ].100| 2 
B3 .185 2 1.175| 2. |.180| -2 180} 2 060| 1 
No explanation of the diversity of results in these two cases 
can be given, but my suggestion is that the effect of the H-ion 
concentration may be more or less related to the availability of 
the food materials of the media, since we know that the sugar 
beet decoction is much more desirable for these fungi than the 
potato decoction. 
Experiment 3.—A modified Richards’ solution was prepared 
which contained 1 gm. ammonium nitrate, 0.5 gm. potassium 
nitrate, 0.25 gm. potassium monophosphate, 0.25 gm. magnes- 
ium sulphate, and 20 gms. dextrose in 1000 cc. of water, and 
hydrogen-ion concentration was adjusted by adding HPO, or 
NaOH. Growing the strains as before the results after a growth 
