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 

 Erysipliei belong also to this connection. The mycelium of 

 Erysiphe cichoracearum, like that of other species, consi&ts 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, 



FIG. 100*. 



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 Bary f 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. 

 desSci. Nat." (1866), p. 211. 



f De Bary, "Morphologic und Pliys. cler Pilze," cap. v. p. 102. 



