85 



Starch agar. This medium proved to be of but slight differential 

 value. The growth was of a dark color and of somewhat bluish tinge. 



Bean agar. H. Nos. 1, 3, 5, 13, 20, grew well on bean agar, all de- 

 veloping a dense, woolly, gray aerial mycelium. Zonation was poor, or 

 obscured by the aerial mycelium. The five strains showed no differences 

 in growth on this medium, which was therefore poor for differential use. 

 In Freudenreich flasks there was a definite black surface-line and much 

 tawny aerial mycelium in clumps. 



Brazil-nut agar. (Formula according to Spencer, 108.) H. No. 1 in 

 test-tubes grew very rapidly and luxuriantly with small development of 

 aerial mycelium and a distinct black basal line. The agar was rapidly 

 cleared of proteid precipitate by the development of a proteolytic enzyme. 

 In Petri dishes a thick, dense, woolly, snow-white aerial mycelium devel- 

 oped which entirely curtained the surface-blackening. The colony was 

 surrounded by a broad translucent zone due to proteolytic action. This 

 agar is valuable for the pure-white aerial mycelium that develops on it, 

 and to demonstrate readily the proteolytic action, though it did not, 

 even in these regards, prove to be differential, since all of fifteen strains 

 tested upon it gave nearly identical responses. 



Oat agar. H. No. 1 at 10 days gave a distinct black surface-line 

 and very heavy aerial gray growth. H. Nos. 1, 4, and 14 were indistin- 

 guishable on it. 



Apple-fruit agar. H. No. 1 gave a black basal line and abundant, 

 sooty aerial mycelium. H. Nos. 1, 4, and 14 were alike except that No. 4 

 produced large sclerotia. 



Apple-bark agar. H. Nos. 1, 4, and 14 grew very slowly and were 

 very dense and black, with but little aerial mycelium. 



Czapec agar. H. No. 1 gave a black surface-line and no aerial my- 

 celium. H. Nos. 4 and 14 were of the same character except that No. 4 

 produced a considerable quantity of smoky aerial mycelium. 



Prune agar. H. Nos. 1 and 4 gave a dense, black surface-growth but 

 no aerial mycelium. 



SUMMARY CONCERNING GROWTH ON AGARS 



Corn-meal agar made by the usual 60 formula proved most useful, and 

 the best differential agar. If made at 100 or at 43 it lacked nutri- 

 ment. The amount of agar used even 25 g. per 1000 c.c. had but little 

 effect on growth characters. Green-wheat agar in varying strengths led 

 to luxuriant vegetation, to little conidia-production, to much abnormality 



