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 Too. 
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- 

Fic. 124 Pucetntia gramints. A portion of a thin transverse section of a leafof FIG. 125. CArysomyxa Rho- 
Berberis vulgaris with a young aecidium beneath the epidermis 7, J section through a dodendri. Basidium from an aeci- 
spot in a Rerberzs leaf containing aecidia. At A is seen the normal structure of the leaf, dium bearing a chain of spores. 
the part #—y’, which contains the Fungus, monstrously thickened ; —o upper surface of Magn. 600 times. For the explan- 
the leaf. sf spermogonia. @ aecidia opened by a section through the middle, » their ation of the figure see page 71. 
peridium. The specimen marked with 2 only without an @ shows the peridium exposed 
by the section in a surface-view. // group of ripe teleutospores bursting through the 
epidermis e from the tissue 4 of a leaf of 7rttzcum repens; t tcleutospores. /// teleuto- 
spores fand uredospores vr. See above, p. 62. 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 farz 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 
172 
