258 BULLETIN 94. 



states that in such cases which came under his observation the 

 conidium only developed a short tube and then soon died. 



The conidia possess a prominent apiculus which in develop- 

 ment is directed toward and rests partly in the stalk of the spor- 

 angium. The sporangium develops from some of the superficial 

 cells of the botryose body, but so far as I have examined from 

 cells which are larger than the usual external cells. The cell 

 begins growth in an upright position or away from the moisture 

 and appears very much like an ordinary vegetative thread which 

 is produced when the plant is immersed in water except that it is 

 greater in diameter. When 6o/j- to 8o//- in length the end becomes 

 enlarged and the protoplasm collects into the forming sporan- 

 gium. While the sporangium is forming the protoplasm is more 

 coarsely granular at the base, while at the terminal portion it is 

 more hyaline, giving the appearance of quite large and rather 

 numerous vacuoles. When the spore is mature it is ejected with 

 considerable force in much the same manner as the spores of the 

 Bntomophthorae. 



The aerial development of the sporangia instead of aquatic is in 

 correspondence with the nonciliated condition of the conidia. 

 One case which came under my observation shows clearly the 

 necessity for the aerial development of the sporangia in the forma- 

 tion of the conidia in this plant. In mounting an affected pro- 

 thallium in water for examination I discovered a partly formed 

 sporangium which projected out into the cavity of an old and 

 emptied ruptured cell. In the growing condition of the prothallia 

 in this case they were somewhat crowded so that they stood more 

 or less erect. The sporangium then in growing also in an erect 

 position away from the moisture would be directed into the empty 

 cell above. Placing this prothallium in a horizontal position on 

 the glass slip in a small quantity of water would immerse the 

 sporangium in the water, or partly so. All of the water was then 

 drawn off except j ust a sufficient amount to prevent the prothal- 

 lium and fungus from drying and the preparation was placed in 

 a moist chamber in order that from time to time it might be ex- 

 amined to watch the development of the sporangium. This stage 

 of the sporangium is represented in figure 43. No farther devel- 

 opment of this sporangium took place. But just at the base of 

 the stalk another one began to be thrown up in a position per- 



