EXPLANATION OF PLATE OPPOSITE. 



I am indebted to Dr. E. A. Letts, Ph.D., &c., President of the 

 Society, for a beautiful series of micro-photographs, which he 

 with great kindness prepared for me, and from which the pre- 

 sent illustrations are copied. 



These micro-photographs were taken from my own mounts 

 of the fungus, that were specially cultivated in small cells on 

 fragments of flies' legs, and fixed for mounting at the different 

 stages of development in the actual position in which they 

 grew. 



No. i. ¥ V A y° un g> developing growth; the darkened 

 ends of the hyphae show the accumulations of protoplasm, and 

 the tendency to form sporanges. 



No. 2. 3L a more abundant growth at a later stage of 

 development, the formed sporanges being nearly mature. 



No. 3. 7 V Increased magnification at the same stage of 

 development as No. 2. The black markings in some of the fila- 

 ments are not natural, but caused by the action of an antiseptic 

 fluid in which the growth was mounted. 



No. 4. y^-Q. Liberated zoospores, just emitted, and the 

 empty sporange that contained them. 



No. 5. t -oq. Oosporangium and oospores, imperfectly de- 

 fined. 



No. 6. -^jj. Dark ground illumination. Number of liberated 

 zoospores and differently shaped sporanges. 



