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INHIBITORY INFLUENCES 
Many influences which inhibit or retard vegetative growth, in so doing 
call forth increased sporulation, in accordance with the second law of 
Klebs (74) that the conditions favoring sporulation are always more or less 
unfavorable for growth. Thus, two colonies of H. No. 1 on washed agar 
were independently nearly devoid of conidia; but when they grew and ap- 
proached each other, vegetative growth was retarded, and eventually in- 
hibited, and each colony became dark in the region of inhibition, owing to 
much-increased sporulation (Fig. 1). Colonies of many other species of 
fungi affected H. No.1 similarly under like circumstances, as did also dry- 
ing out of the agar at the colony’s edge. Similar changes in growth, and 
consequently in colony-character, occur on almost any medium, prom- 
inently on corn-meal agar, and they must be understood and reckoned 
with if colony characters are to be used for descriptive purposes. 
Fig. 1—lIllustrating inhibitory influence on 
sporulation. Two colonies of H. No. 1, on washed 
agar, showing dark bands, due to abundant sporu- 
lation where the colonies approach each other. 
Sporulation also somewhat increased near margins 
of colonies, owing to drying. 
HUMIDITY OF MEDIA 
Rice was placed in tubes with water equal to twice the volume of the 
rice, and with water equal to four times its volume, being then autoclaved 
and inoculated with various Helminthosporiums. Notes at two weeks 
show better characters of border, interstices, etc., in the wetter tubes, and 
while with many strains sclerotia developed abundantly in the drier tubes 
