INTKODUCTION TO CEYPTOGAMIC BOTANY. 



325 



tions can alone clear up all such difficulties, and restrict genera 

 within just limits. The prothallus of Puccinia sometimes 

 exhibits several layers in the epispore (Fig. 73, e), a circum- 

 stance which is not common amongst Fungi. Podisoma and 



Fig. 73. 



a. Aregma speciosum, Fr. From South Carolina. 



b. Xenodochus paradoxus. 



c. Puccinia Amorph(B, Curtis, showing the deciduous outer coat. 

 From South Carolina. 



d. Triphragmium degluhens, Berk, and Curt. From Texas, with its 

 deciduous coat. 



e. Young spores of an unknown Puccinia. From South Cai-olina, 

 showing the numerous layers in the outer coat. 



/. Puccinia lateripes, Berk, and Eavenel, on Euellia. South Carolina. 

 All more or less magnified. 



Gymnosporangium are merely Puccinice with greatly elon- 

 gated stems, and the addition of a gelatinous element. One 

 singularity about them is, that the disc from which they spring 

 produces a new crop year after year, till the mother plant 

 is exhausted and dies ; while in P. macropus the matrix 

 swells into a large globular mass, having the appearance of 

 some Echinus divested of its columnar spines. It is probable 

 that in this case and in Cyttaria, which has similar habits, the 



