296 



MXETEENTH REPORT. 



in one lot of corn meal agar prejjared by a colleague the submerged 

 mycelium extended down to a much greater depth than on the same 

 medium prepared b}- the author. The deartli of spores on potato, how- 

 ever, seems to be constant on several lots of this medium. 



The following tables give a comparison of the growth on the various 

 media, under as uniform conditions as it was possible to obtain. As a 

 quantitative standard of growth, oat meal agar was used for the various 

 agar media, sugar beet for the vegetables, and clover juice for the liquids. 



Table 4. 



Growth on Liquid Media: Small Flasks. 



6 days. 

 Colonies dark graj^, 2-8 

 mm. diameter. A ring of 

 colonies has formed where the 

 Clover juice. liquid touches the glass. Bot- 



tom of flask completely cov- 

 ered by white mycelial mat 

 consisting of many small 

 colonies. Spores being formed. 



21 days. 

 Most of the colonies have 

 grown together, forming a 

 heavy, black spore covered 

 mat. Mycel. on bottom also 

 dense but bears no spores. 

 Best growth obtained from 

 liquid media. 



Full nutrient 

 solution. 



Good surface growth but 

 light in color. Dark ring of 

 colonies around edge of liquid. 

 Spore production slight. 



Heavy growth of mycelium 

 throughout the liquid, but 

 spores are not abundant. 



Coons' ^Synthetic Medium same as Full Nutrient Solution. 

 Dunham's Peptone Sol. same as Full Nutrient Solution. 



'Coons, G. H. (1916). 



