90 



of the same species (e. g., H. Nos. 5 and 6), and between H. No. 20 and No. 

 13, presumably of the same species, and therefore they are not of reliable 

 taxonomic value. Even at the end of three months there were no sclerotia, 

 pycnidia, or perithecia in any of the tubes. Ravn (91) has stressed the 

 importance of sclerotia (which this medium yielded in his jstudies) as a 

 means of distinguishing certain races or species; but no such value attaches 

 to it for the races that I had under observation. 



Fresh wheat-leaves. Green wheat-leaves were prepared in the same 

 manner as the wheat straw. On these leaves growth of H. No. 1 was 

 much as on the w r heat straw except that many more conidia were pro- 

 duced both on the lower portions of the leaf and on the water-surface. 

 On the upper part of the leaf, about 6 cm. above the level of the water, 

 where the leaf was too dry for conidia-formation, a rather extensive, white, 

 floccose, loose aerial mycelium developed. 



SUMMARY CONCERNING THE FOREGOING VEGETABLE MEDIA 



"But little of differential value resulted. The characters of aerial 

 mycelium, sclerotia, clumping of mycelium, and pellicle-formation were 

 but slightly marked, all being highly dependent on conditions of environ- 

 ment. 



CEREAL SHOOTS GROWN FROM ASEPTIC SEEDS AS MEDIA 



Cereal seeds were disinfected and sprouted in sterile moist cham- 

 bers. When the shoots were 2-3 cm. long they were cut off, placed in 

 water in a test-tube, and autoclaved. Next, washed agar was placed in 

 Petri dishes and inoculated with H. No. 1. About four days later, when 

 the colonies were several centimeters in diameter, various cereal shoots, 

 prepared as above, were laid on the washed-agar plates, the basal end of 

 the shoot in each case touching the edge of the colony. In this way re- 

 peated tests were made w r ith wheat, oats, corn, rye, and barley, with the 

 invariable result that growth was most luxuriant and dense on the corn, 

 which soon became completely black. No constant difference was evident 

 between the other cereals, except that rye seemed a medium slightly less 

 favorable than the others. 



It seemed probable that the more luxuriant growth and conidia-devel- 

 opment on the corn shoots was due to quantity rather than to quality of 

 nutrients. To test this hypothesis an entire corn shoot, a longitudinal 

 half of a shoot, a longitudinal quarter of a shoot, and a mere longitudinal 

 filament were laid on a colony of H. No. 1 growing on washed agar. On 

 the smallest fragment, growth and conidia-production were about as on 



