149 
that no conidia indicating contamination were present, therefore, if the 
colony were parasitized it must be either by a mycelium like that of 
Helminthosporium and without conidia, or by some virus of un- 
known character. To test this possibility well-established colonies of 
H. No. 1 were inoculated with such striking saltants as M84. Transfers 
of M84 were also made to points near the circumference of the H. No. 1 
colony. If M84 bore a parasite of any kind this parasite might be ex- 
pected to invade and overgrow the H. No. 1 colony. This it did not do, 
but the two colonies halted a few millimeters apart in the manner char- 
acteristic of two Helminthosporium colonies. It is quite clear that the 
idea of colony parasitism is untenable in this connection. 
Position of inoculum.—Since it was possible that the differing appear- 
ances presented by the various sectors might be due to the position of the 
mycelial strands in or on the agar, that is, on top of it, in it, or below it, 
tests were made in three ways: 1, by placing conidia in an oese of water on 
the surface of poured agar; 2, by similarly placing conidia, without water, 
in a shallow scratch made in the agar; 3, by so cutting the agar that a flap 
about a square centimeter could be lifted and inoculated on the lower side, 
that is, the side in contact with the glass, the flap being then put back in 
place. These three modes of inoculation resulted in colonies of indistin- 
guishable character. 
SALTATIONS FROM SINGLE CONIDIA 
Eight separate pure cultures were made from single conidia. The 
eight colonies were under careful microscopic control from the time of 
planting the conidia, through germination, and until the colony was well 
developed, and it is certain that in each instance the colony was from a 
single conidium. These pure strains, all alike in colony character, were 
labeled C1, C2, C3, etc. Well-marked saltants appeared in four of them 
as follows: 
( P 
Caren. { 
| 110 
108 
(ere 
100s wena emcee en 
| 120 
