CHAPTER V. COMPARATIVE REVIEW. -UREDINEAE. 



275 



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

 ellipsoid and filled 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 zoo. 



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- 



t/L 



FIG. 124. Piifdnia grnmitiis. A portion of a thin transverse section of a leaf of FIG. 125. Chrysomyxa Rho- 



Ktrberis uulgaris with a young aecidium beneath the epidermis . / section through a dodrndri. Basidium from an aeci- 



spot in a Herberts leaf containing aecidia. At X is seen the normal structure of the leaf, diura bearing a chain of spores, 



the part y 1 , which contains the Fungus, monstrously thickened ; h o.upper surface of Magn. 600 times. For the explan- 



the leaf, sp spermogonia, a aecidia opened by a section through the middle, f their ation of the figure see page 71. 



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 A of a leaf of Triticum repens ; t teleutospores. /// teleuto- 

 spores / and uredospores ur. See above, p. (a. From Sachs' Lehrbuch. / slightly magni- 

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



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 jjt 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 





