176 FUNGI. 



jugated cells, especially the larger, wither and empty themselves, 

 while the upright compressed filaments, which will ultimately 

 constitute the asci, increase and multiply.* 



Certain phenomena concerned in the development of the 

 Erysiphei belong also to this connection. The mycelium of 

 Erysiphe cickoracearum, like that of other species, consists of 

 branched filaments, crossed in all directions, which adhere as 

 they climb to the epidermis of the plant on which the fungus 

 lives as a parasite. The perithecia are engendered where two 

 filaments cross each other. These swell slightly at this point, 



and each emits a process which imitates a nascent branch, and 

 remains upright on the surface of the epidermis. The process 

 originating from the inferior filament soon acquires an oval form 

 and a diameter double that of the filament; then it becomes 

 isolated from it by a septum, and constitutes a distinct cell, 

 which De Baryf terms an oocyst. The appendage which pro- 

 ceeds from the inferior filament always adheres intimately to 

 this cell, and elongates into a slender cylindrical tube, which 



* Tulasne, "On the Phenomena of Copulation in certain Fungi," in "Ann. 

 des Sci. Nat." (1866), p. 211. 



t De Bary, " Morphologic und Pbys. der Pilze," cap. v. p. 162. 



