RUSTS. 99 



minute,, cellular, linear bodies called spermatia, in- 

 vested with a kind of mucous substance, that over- 

 flows with them from the orifice of the spermogone, 

 like lava from the crater of a miniature volcano. 

 The rust in company with which they have been 

 found most plentifully, is that which covers the 

 under surface of the leaves of the commonest of 

 all thistles (Gnicus arvensis). The external form of 

 one of these spermogones is figured plate VII. 

 fig. 153. The rust possesses, when fresh, a pecu- 

 liar odour, which is said to resemble that of orange- 

 flowers ; whence was derived its name of " sweet- 

 smelling rust" (Trichobasis suaveolens, Lev.). M. 

 Tulasne writes : — " With respect to this species, it 

 is, in my opinion, but the first form of a Puccinia, 

 analogous to P. Compositarum, D.C. : the spermo- 

 gones with which it is mixed being very abundant, 

 it ought to be placed with that Puccinia. I should, 

 perhaps, retain some doubts upon the legitimacy 

 of this relationship, if it had not been my fortune 

 to meet on another species of the same kind (Puc- 

 cinia Anemones, P.) spermogones perfectly charac- 

 terized, and in which the colour, habit, and position 

 would not allow me to hesitate an instant in at- 

 tributing them to the Puccinia. }} In this species of 

 rust the whole under surface of the leaf is covered 

 with a purplish-brown dusty coating of the spores, 

 from th^ numerous pustules which are produced 

 (plate VII. fig. 151). The plants, when attacked, 

 have a paler and more sickly appearance j the leaves 



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