Ill 



The protoplasm in all parts of the plant is gray, and of a coarse, gran- 

 ular nature. 



The mycelium evidently meets with some resistance in passing from 

 cell to cell of the host, for at these places it is often more or less knotted 

 or bent, always on the same side of the cell wall with reference to the direc- 

 tion of growth in the filament, as if it had not been able to penetrate the 

 cross wall immediately. (Fig. 6.) These penetrations of the cross wall 

 are seldom through the center, but usually far to one side of the filament. 



The plant is describe'd as producing zoospores in long slender sporangia, 

 but, in this case, no asexual spores of any kind were observed. Oospores, 

 however, were produced in abundance by the union of gametes which, in 

 no case, were found to arise from the same filament. 



The sex organs arise as the enlarged ends of short lateral branches of 

 the mycelium and usually api)ly themselves to each other very early. (Fig. 

 1.) The oogdiiiuni iiiiiiicdiately develops rather large, (•onical jirojections 

 all over its surface. (Fig. 2.) The antheridinm remains small, club- 

 shaped, and nearly transparent even to maturity. 



The conjugating tube is formed when the oogonium Is still young and 

 before all its oily content has been organized into the egg. (Fig. 3.) At 

 about this time the oogonium is cut off by a cross wall, but, to all appear- 

 ances, the antheridium remains continuous with the rest of the mycelium. 



The mature oospore is about 36 microns in diameter ; the spines are 

 from 5 to S microns in length. (Fig 4.) The heavy wall of the siiore, 3 

 lo 4 microns in thickness, is a very serviceable adaptation for enabling the 

 plant to live through conditions unfavorable for its growth. 



The writer is indebted to Professors Mottier and Van Hook for assist- 

 ance in indeutifynig this fungus and for valuable suggestions as to methods 

 of studying it. 



