PEIUSPOBIACE^. 



279 



tilization. The sexual organs and the sporocarp resulting 

 from the act of fertilization bear a striking, resemblance to 

 those of ColeochcBte, the difEerence being such as may be ac- 

 counted for by considering the aquatic habits of the one, and 

 the aerial and parasitic or saprophytic habits of the other. 



373. — In the parasitic PerisporiacecBih.e jointed filaments 

 of the mycelium closely invest and cover the leaves and 

 other tender parts of their hosts, and draw nourishment 

 from them by means of haustoria, which project as irregular 

 pullulations from the side of ^ 



the hyphaB next to the epider- 

 mis (Fig. 187) ; these haustoria 

 apply themselves closely to the 

 epidermis cells, and, in some 

 cases at least, appear to penetrate 

 them.* The crossing and rami- 

 fying hyphae soon send up many 

 vertical branches, in which parti- 

 tions form at regular intervals ; 

 the cells thus fojrmed are at first 

 oblong and cylindrical, with flat- 

 tened ends ; but the topmost one 

 soon becomes rounded at its ex- 

 tremities, and the others follow ^^g xs?.-Brysiphe maiune, 

 in qiuck succession, thus givmg ^J^::^X4oT.f..l^if^^. 



rise to a monilif orm row of loose- epidermis of the leaf of the vine, and 



, ,, , 1 IT ,• n in to which it Is fastened by the haus- 



ly attached elliptical or roundea toria. h; 6, an isolated piece of a 



1, ,, • T I T -nt- ioo\ vegetative hypha, with the hausto- 



eellS, the comma {1, i^lg. 1»»). rium, a, seen fn side view. X 370.— 



These fall ofE and germinate at ^'"'^™^°"- 



once by pushing out a germinating tube, which gives rise 



to a new mycelium. ■ 



374. — The sexual process, which in most species takes 



* De Bary (" Morphologie und Physiologie der Pilze," etc., 1865, p. 

 19) pays that the haustoria of the investigated species do not penetrate 

 into the epidermis cells ; while Sachs (" Lehrbuch, 4te Auflage," 1874, 

 p. 313) says that haustoria are sent into the epidermis cells. A myce- 

 lium on Poa pratensis (probably of Erysvplie communis) examined in 

 1877 appeared to have sent its haustoria through the outer walls at 

 the epidermis cella 



