324 INTRODUCTION TO ORYPTOGAMIC BOTANY. 



noticed, as it is one of the most curious in the group. The 

 spore in this case is of considerable size, and evidently reticu- 

 lated, and below it, either free or in contact with the stem, is 

 a circle of colourless bags, foreshadowing a more complicated 

 system of articulation than even in the follo-vving group. The 

 germination of these has not at present been observed. It is 

 probable that the number of threads to which the spores give 

 rise is considerable. 



2. PucciNi^i, Berh. 



Mycelium traversing the cells of living plants, mostly deli- 

 cate, giving rise to short or elongated fertile threads, terminated 

 by more or less elongated septate spores. Spores, when ger- 

 minating, pi-oducing a second order of spores. 



850. The species of this group differ from the last merely in 

 the circumstance of their spores or prothallus being more com- 

 plicated. The circumstances of germination, growth, &c., are 

 precisely the same, and require but little addition. They do 

 not in general distort the matrix so much, and are remarkable 

 for their rich golden brown hues, which in some is exaggerated 

 into deep bay. In some cases, as in a beautiful sjjecies from 

 South Carolina, a granulated episperm separates from the pro- 

 thallus; and in the singular genus Sartvellia (Fig. 72, a), 

 either division is crowned with a large number of short pro- 

 cesses. One circumstance is worthy of note, that more than 

 one species of Puccinia sometimes occurs in the same pustule ; 

 but not only is this the case ; Uredines and Puccinice very 

 commonly coexist. In Uredo linearis, the so-called spores are 

 merely the early stage of Puccinia graminis. But not only 

 are these species ascribed to Uredo, though not really autono- 

 mous, but many species of Puccinia are accompanied by 

 bodies simulating exactly those of Uredo, though, in fact, only 

 secondary forms of fruit. This is most remarkable in the 

 genera Aregma and Xenodochus (Fig. 73, a, b), which are 

 not to be regarded as doubly parasitic, but as species present- 

 ing twofold fruit in one pustule. Such considerations will 

 eventually reduce the species of Uredo to a great extent ; but 

 we are not to suppose that there are therefore no autonomous 

 species of that genus. Length of time and multiplied observa- 



