CHAPTER V. — COMPARATIVE REVIEW. — UREDINEAE. 



175 



been ascertained. The spores are between round and polyhedric, more rarely 

 ellipsoid and rilled with a dense protoplasm, which is sometimes colourless, but is 

 more commonly coloured by a reddish yellow oil; the walls of the spores are 

 colourless or of a brownish colour, and often show the prismatic structure described 

 on page ioo. 



The hymenium and the rows of spores which proceed from it are enclosed 

 in a membranous envelope composed of a single layer of cells (the peridium, pseudo- 



\G&> 



FIG. 124. Pitccimti graminis. A portion of a thin transverse section of a leaf of 

 Berberis vulgaris with a young aecidium beneath the epidermis 11. I section through a 

 spot in a Berberis leaf containing aecidia. At X is seen the normal structure of the leaf, 

 the part u—y' t which contains the Fungus, monstrously thickened ; k — upper surface of 

 the leaf, sp spermogonia. a aecidia opened by a section through the middle, / their 

 peridium. The specimen marked with / only without an a shows the peridium exposed 

 by the section in a surface-view. // group of ripe teleutospores bursting through the 

 epidermis e from the tissue b of a leaf of Trilicum repens ; t teleutosppres. /// teleuto- 

 spores t and uredospores ur. See above, p. 62. From Sachs' Lehrbuch. / slightly magni- 

 fied, // magn. 190, /// 390 times. 



FIG. 125. Chrysomyxa Rho- 

 dodendri. Basidium from an aeci- 

 dium bearing a chain of spores. 

 Magn. 600 times. For the explan- 

 ation of the figure see page 71. 



peridium or paraphyses-envelope) ; the cells of the envelope are in rows like the 

 spores, and it grows pari passu with the chains of spores and by the constant 

 addition of new elements from the base. This growth is effected by a compact 

 annular row of cells, like basidia, which occupy the margin of the hymenium, 

 and it advances therefore exactly in the same way as that of the spore-chains, but 

 without forming intermediate cells. The cells of the envelope are united laterally to 



t 2 



