106 C. D. Sherbakoff 



For determination of the color of the substratum and also for study of the 

 colony growth, it would perhaps be best to use poured plates with about 

 10 cubic centimeters of a clear agar. In this work potato hard agar with 

 from 5 to 10 per cent of glucose was almost exclusively used for this pur- 

 pose. For the stud}^ of other characters, in most cases cultures were made 

 in common test tubes. 



EFFECT OF VAEIOUS MEDIA ON DIFFERENT CHARACTERS OF FUSARIA 



In the course of this work it was observed, in partial confirmation of 

 the statement by Appel and Wollenweber (1910 : 12-23), that certain media 

 affect fungous growth more or less characteristically. A medium too 

 rich in nutrients, especially in glucose, usuaUj^ gives cultures with more or 

 less abnormal spores, the abnormality showing itself in a too dense granula- 

 tion of the protoplasm, in more or less considerable swelling of the spore 

 cells, and often in abnormal septation, size, and shape. 



Media rich m glucose usualty increase the density of color produced by 

 these fungi, and often also change its character. For example, a pink 

 fungus, F. arcuosporum, is turned to a clay-colored one; or the fungus 

 F. angustum, which is colorless or nearly so, is turned to a more or less 

 bright purplish- vinaceo us one; and so forth. 



Excess of water in a medium usually leads to comparatively quick 

 degeneration (self-digestion ?) of the spores, and, in general, to a shortened 

 duration of the vitalitj^ of the culture. Its presence, at least in case of a 

 soft agar as compared with a hard agar, is usually unfavorable for the 

 normal development of aerial mycelium. 



A medium comparatively poor in nutrients, such as corn meal agar, 

 seldom gives rise to sclerotia and plectenchymic sporodochia; but in 

 a way it is a good medium for the study of chlamydospores, which are 

 produced here more or less freely and stand out more clearly than in other 

 media. 



Whole potato tubers (steamed) often are most favorable for production 

 of large sporodochia; this medium, and also potato tuber plugs (also 

 steamed), show the largest sclerotia.^^ 



An agar, especially such a one as oat hard agar, often gives aU the forms 



" See also Wollenweber (1913 a: 25). 



