1921] 
MATSUMOTO—SPECIALIZATION IN RHIZOCTONIA 41 
then inoculated with each one of these squares. In cases where 
the plates were inoculated with the squares of P1 x P4, Pl x 
P7, H x P4, or H x P7, the growth of P4 and P7 was always 
inhibited by the accompanying strain and no further growth 
was noticed, while, on the other hand, when the squares with 
P1 x BlorH x B1 were used, the results were entirely depend- 
ent upon the environment. For instance, if the plates were 
immediately incubated at rather high temperatures, growth of 
the strain P1 or H was inhibited by the strain B1, and the plates 
were entirely covered by the latter, while if the cultures were 
incubated at a rather lower temperature, quite the opposite 
result was noticed. In no case was there evidence that heter- 
ozygosis occurred. Growth of the strain B3 was very slow and 
always covered by growth of the other strains so that no data 
may be secured for this form in contact with others. 
In spite of the data presented, these results must be regarded 
as preliminary, and in further work cytological technique should 
be employed. 
AERATION 
With various fungi experiments have shown that the effect of 
inadequate aération is repression of growth or suppression of 
fruiting stages. In order to determine the relation to aération 
in Rhizoctonia a series of flasks of different sizes were used. 
Fifty cc. quantities of sugar beet decoction were pipetted into 
each flask. Immediately after inoculation with the 6 strains 
the cotton plug was pushed slightly down into the neck of each 
of the flasks and then sealed with melted paraffin. The results 
after one month are as follows: 
TABLE XXVII 
THE INFLUENCE OF AERATION ON GROWTH pie eo FORMA- 
TION, DRY WEIGHT IN GRA 
Size of flasks 
: | Control, 
Strains 1000 cc. 500 cc. 250 cc. 125 cc. | 125 c 
Growth | Sel. | Growth |Scl. | Growth |Scl. | Growth | Scl. | Growth | Sel. 
IET 205 | Rare 090 | No}. .025 | No 020 | No| 1.065 
P4 145 | Rare 040 | No .020 | No 015. | No 540 
IB 180 No 085 |No| .030 | No 010 | No 820 | No 
B1 Negl No | Negl. |No| Negl. | No| Negl. | No| Negl. | No 
H 225 | Rare 100 |No| .025 |No 020 | No 980 
B3 Negl No Negl. | No| Negl. | No| Negl. | No} Negl. | No 
