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 cichoracearum, 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, 
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} 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. 
+ De Bary, ‘‘ Morphologie und Phys. der Pilze,” cap. v. p. 162. 
