MICHIGAN ACADEMY OF SCIENCE. 295 



vegetable plugs, and liquids. All cultures in each group were run simul- 

 taneously, and growth observed over a period of three weeks. 



In general, growth proceeds as follows: The spores germinate within 

 a few hours and after 24-28 hours, small white tufts of aerial mycelium, 

 1-3 mm. long appear. During the next two or three days the mycelium 

 spreads gradually over the surface of the medium, the rate of spread 

 depending upon the amount of moisture present and the amount of 

 inoculum used. Beginning with the third day, the mycelium usually 

 darkens in color, at first a dull gray woolly appearance wliich gradually 

 darkens. Spore formation begins on the fifth or sixth day, and as the 

 spores mature and increase in number, the culture assumes a black, felt- 

 like appearance. On agar media, the fungus usually begins to grow down 

 below the surface after the first week. This submerged growth which 

 may extend down 5-10 mm., consists of a dark mycelium and spreads out 

 more or less like the roots of a plant. The maximum amount of growth 

 is reached within 16-20 days. 



Of the various agar media used, oat meal agar produces the most 

 abundant growth of mycelium and spores. Plain nutrient and synthetic 

 agars produce the smallest amount of growth. With the addition of 

 glucose or dextrose to the nutrient agar, growth materially increases. 



Of the vegetable media used, it is noteworthy that on potato, while 

 a dense mycelial growth was produced, spores were few. The presence 

 of sugar seems to favor spore production. Of these media sugar beet 

 and red table beet rank first in the amount of spores formed, carrot 

 second, parsnip third, and potato last, which also represents, approx- 

 imately, the relative order of their sugar content. If glucose is added 

 to potato, as in the case of hard potato agar, spores grow in abundance. 

 On the other hand, wheat stai'ch paste (Kahlbaum's) is an excellent 

 medium for spores. A test of tlie substratum upon which the fungus had 

 been growing for two weeks showed that much dextrose had been formed. 

 The sterile, uninoculated starch paste check gave no such test. Evidently 

 the fungus secretes diastatic enzymes. 



On the plain corn meal, growth is abundant, but tlie hypothetical ascus 

 stage has thus far failed to appear on this medium. (Oldest culture, 

 nine months.) Clover stems, bean pods, and sorghum stems, are very 

 good media for obtaining an abundance of spores. 



There are no striking differences in the general appearance of the 

 fungus on the various media studies. All cultures look more or less alike 

 and can be distinguished from each other only in a comparative series. 

 The gross amount of growth and the abundance of spores varies to a cer- 

 tain extent even on the same medium. Again organic media are not 

 always alike even if prepared imder the same formula. Eor example. 



