3 



aourishmeht. These haustoria present several fortas, and they are of 

 some importance in tlie classification of the species. In some cases the 

 haustorium simply consists of a slender tube which penetrates the epi- 

 dermal cell of the host, within which it swells to an oval or club-shaped 

 sac, filled with granular protoplasm. More often there is an external 

 appendage or sucker, that is pressed close to the surface of the epider- 

 mal cell, and from this, or from near it on the mycelial thread, the 

 haustorium proper takes its rise and penetrates the epidermis. This 

 external appendage may be smooth and entire, merely constituting a 

 hemispherical swelling on the mycelial thread, or, it may take the 

 form of a flattened disk with an indented margin. In the latter case 

 it is said to be " lobed," in the former, " not lobed." 



The conidia, or asexual reproductive bodies, are cylindrical, oval 

 or nearly orbicular, simple, colorless cells filled with protoplasm. 

 They are formed by constriction at the ends of short, simple, erect, 

 rather stout, septate, colorless branches of the mycelium, called fertile 

 hyphae or conidiophores, A septum forms near the end of the young 

 hypha, and the walls at this point become constricted. The cell thus 

 cut off usually swells a little, and at length falls away as a mature 

 conidium. Before this happens, however, other constrictions have 

 taken place below, thus forming a chain of nearly mature conidia 

 adhering end to end. Under favorable conditions they germinate 

 quickly, sending out a slender tube, which, on the proper host, soon 

 develops into a new mycelium. They are produced in immense num- 

 bers throughout the growing season, and, as they are very light and 

 easily carried by the wind, they serve for the rapid increase and wide 

 distribution of the parasite. 



The perithecium remains on the fallen leaves over winter. It is 

 not provided with a mouth or ostiolum of any kind. The contained 

 asci and sporidia only escape on its decay in the spring. 



Delicate membranaceous conceptacles, other than the perithecia, 

 are sometimes found in connection with the mycelium of the Erysi- 

 phece. They are thin-walled, and, on slight pressure, rupture irregu- 

 larly, emitting immense numbers of minute, oblong, nucleated spores, 

 immersed in a gelatinous fluid. They were noticed by Cesati, in con- 

 nection with the grape mildew. Supposing them to be independent 

 organisms, he named them Am.pelomyces qidsqualis, and specimens 

 were published under that name as No. 1669 in Rabenhorst's Herba- 

 rium Mycologicum. Later they were called Cicinobolus Jlorentinus 

 by Ehrenberg, and Byssocystis textilis by Eiess. Tulasne, Mohl, 



