30 MICROSCOPIC FUNGI. 



briglit yellow^ as are afterwards tlie cups and spores 

 of the j^cidium. In most instances tiie appearance 

 of the spermogones precedes that of the sporiferous 

 organs, but the latter follow sufficiently speedy for 

 perfect development before the decadence of the 

 spermogones takes place. 



After the expulsion of the spermatia and the fluid 

 which accompanies them, the whole mass dries up ; 

 and where many spermogones have been clustered 

 together in the same spot a brown homogenous 

 crust is formed upon the epidermis ; where they are 

 produced singly, a brownish incrustation is visible 

 about the mouth of each spermogone. 



Ee-agents apphed to the spermogones whilst in 

 full vitality indicate the presence of a considerable 

 amount of a protein substance, which, with sugar 

 and sulphuric acid, produces a deep pm-ple red colour. 



From what we have already stated of the method 

 of occurrence of these organs, the following is the 

 only order, apparently, preserved in their develop- 

 ment, although no definite rules can at present be 

 affirmed. The spore spots of cluster-cups are 

 generally found upon the under surfaces of the 

 leaves on which they are produced, and the spermo- 

 gones are most numerous on the upper. When 

 both the cluster-cups and the spermogones appear 

 in the same group on the same surface, the sper- 

 mogones commonly occupy the centre, and the 

 cups are arranged in a circular manner about 

 them. In other, and fewer instances, both 



