Ch. X] 



THE TOADSTOOLS 



469 



and infect only other leaves of those plants; but later in 

 the season appear hair-like structures on which are developed 

 many teleutospores. These, also disseminated by the wind, 

 infect not Currants but White Pines, in which they produce 

 the effects already described. This alternation of hosts 

 seems invariable, and offers, through destruction of the Cur- 

 rant and Gooseberry bushes, the only known method of 

 combating the disease. 



Another member of this group (Gymnosporangium) , hav- 

 ing its aecidial stage on Hawthorns and Apples, causes the 



Fig. 327. — The common edible Mushroom, Agaricus campestris; X \. 



On the right, a section across several gills, X 2 ; a section across one 

 gill, X 10; and a portion of one gill showing mycelium, hymenium, and 

 basidia, with basidiospores, X 25. (From Bailey, and Sachs.) 



swollen gall-like growths called Cedar Apples on Red Cedar, 

 while other members of the same group produce the largest 

 Witches' Brooms (often called " Hurrah's Nests" in this 

 country) upon Spruces and Firs, as earlier described (page 

 198; Fig. 147). And there are many other striking kinds, 

 some having but one host, well known to experts in the subject. 

 The Uredinales are connected with the Hymenomycetes by 

 intermediate forms, commonly treated as separate orders, of 

 which the Ear Fungi (Auriculales) , and certain Gelatinous 

 Fungi (Tremellales, Fig. 326), are most prominent. 



