LABORATORY STUDIES 197 



Mount a few filaments (as directed in i above) and examine 

 filaments, sporangia, and spores. 



(k) Moisten a piece of bread and then sow here and there on 

 its surface a few spores of Black Mold; cover with a tumbler or 

 bell glass. In a few hours a new crop of Black Mold will begin 

 developing. The nutritive mycelium may be studied by 

 teasing out small bits of the newly infected bread. 



(0 Place several clean glass slides in contact with a culture of 

 black mold, as described in (k). By removing these at different 

 times the various stages of growth of the mold may be easily 

 studied. 



(m) Collect a number of large fleshy fungi (Boletus, Lactaria, 

 Agaricus, etc.) and place under bell jars for a couple of days. 

 Usually a cream-colored mold (Sporodinia grandis) will begin 

 to develop upon some of these. Transfer it to pieces of bread 

 as in (k) and study in a similar way. After a few days the 

 zygospore formation will be observed, as this species is homo- 

 thallic. 



(ri) In the latter part of summer and in the autumn examine 

 the dead flies which adhere to windowpanes, door-casings, and 

 especially to wires and strings hanging from the ceiling. The 

 whitish powder around the fly will indicate the presence of the 

 Fly-fungus (Entomophthora muscae). Mount some of this 

 white powder in water and examine under a high power. Tear 

 out small bits of the distended abdomen of the fly, and examine 

 for internal portions of the parasite. 



(o) In the autumn look for dead grasshoppers attached to the 

 tops of weeds and grasses. Examine their interior tissues for 

 thick-walled resting spores of Entomophthora grylli. 



(p) In damp weather in the summer look for Botrydium on 

 the hard, smooth ground of unused paths. It often appears 

 on compact soil in greenhouses in the winter. 



(<?) Specimens of Valonia, Bryopsis, Caulerpa and Acetabu- 

 laria may be obtained of dealers in laboratory material for 

 study and examination. 



(r) Search the sandy margins of ponds, lakes, and slow streams 

 for Stoneworts (Charales). They are generally found in water 

 from a few centimeters to one or two meters in depth. Pre- 

 serve such specimens temporarily in water which is frequently 

 changed, but for future use preserve in alcohol. Study as 

 follows. 



