100 



bottom up, and observed carefully, but 

 of growth was observed. 



GROWTH OF H. No. 1 IN THE DARK AND IN THE LIGHT 



CARBOHYDRATES 



Brazil-nut agar in Petri dish with H. No. 1 gave snowy white colonies. 

 When such colonies had reached a diameter of about 3 cm. one oese of 

 powdered dextrin, maltose, rhamnose, or glucose was placed on the agar 

 a few millimeters from the advancing edge of the colony. Within 48 hours 

 the portion of the colony near the added carbohydrate, with the exception 

 of rhamnose, produced conidia in much greater abundance than before, and 

 the mycelium turned slightly dark. Starch, corn-oil, and corn-meal pro- 

 duced a similar effect, but with delay of nearly 48 hours, suggesting that 

 the additional time required was needed for the production and action of 

 enzymes, diastase, or lypase, as the case might be. 



Again, plain-agar plates were poured and inoculated with H. No. 1, 

 and when the colony was well developed various carbohydrate nutrients 

 were laid on the agar near the advancing edge of the colony: steamed rice, 

 steamed tapioca, 1 square centimeter of standard corn-meal agar, a frag- 

 ment of a Brazil-nut, corn-starch, wheat flour, corn-meal, and buckwheat 

 flour. All of these nutrients were used, and in each case the colony in the 

 region of these nutrients turned black, owing to the quantity of conidia pro- 

 duced (PI. XVI). Ravn (91) noted a distinct relation between carbohy- 

 drate nutrients and blackness in Helminthosporium, as did I in various 

 fungi (118). 



On plain agar, glycocoll and aspartic acid inhibited strongly at first, 

 but later the fungus grew through these. It grew normally through ty- 

 rosine, glutamic acid, leucin, cystine, phenyl, and alanine without percep- 



