ZYGOMYCETES 



349 



resting progametanges, with a stratified membrane and dense contents. 

 These persist when the mycele dies, and hibernate. After this period 

 of rest, and on liberation from the decaying tissues of the host (in 

 water), the intine, with the contents, bursts the extine, and, becoming 

 free, constitutes the gametange. Within it a large number of minute 

 short rod-shaped gametes are formed, while a portion of the proto- 

 plasm remains unused in the process. These gametes are ejected, 

 and, being without the power of spontaneous movement, they remain 



FIG. 298. Protomyces macrosporns Unger. a, a mature resting progametange ; b, gametange ; c, d, 

 and e, further stages of the same in the development of gamete?, c shows the parietal protoplasm,. 

 d the same divided into gametes, e the gametes rounded off and separated from the rest of the parietal 

 protoplasmic layer ( x 390). (After de Bary.) 



in more or less proximity to each other. Where pairs of gametes 

 come together, they emit fine processes which conjugate, the whole 

 having the appearance of a dumb-bell or of the letter H. The germi- 

 nation of these has been observed on the epiderm of ^Egopodium ; it 

 takes place by the emission from one of the original gametes of a 

 germ-tube, to the nourishment of which the protoplasm of the united 

 gametes contributes. This germ-tube, on entering the tissues of the 

 host, repeats the life-history. 



LITERATURE. 



De Bary Beitr. zur Morph. und Phys. der Pilze, i. 

 Von Thiimen Eine neue Protomyces Species (Hedwigia, 1874). 

 Wolff See footnote to de Bary's paper ' Protomyces microsporus und seine Ver- 

 wandten' (Bot. Zeit, 1874, p. 82). 



Oilier literature of systematic interest in Saccardd's Sylloge. 



ORDER 5. USTILAGINE^:. 



The parasites which are grouped together under this name affect 

 Flowering Plants of different natural orders, but are especially conspi- 



