414 ARTHUR AND MAINS: GRASS RUSTS 
. Puccinia phakopsoroides illustrates an extreme development 
in this general direction, most strongly seen in the telia. Drawings 
of the telial sorus of both P. phakopsoroides and P. pallescens 
(Fics. 1A, 2A) show the spores as cylindrical bodies pressed very 
closely together, as if restricted by the unyielding epidermis. 
The spores appear to be less highly differentiated than in most 
grass rusts, having a variable number of cells with a quite uniform 
wall, and a pedicel so short and delicate that one is left in doubt 
whether there is a truly pedicellate cell, or only a hyphal connec- 
tion with the hymenial layer of the fungus. 
Sections of the sorus give a superficial resemblance to forms 
of Phakopsora, especially in the denseness, the pale color and trans- 
lucency, and in the evenly disposed, vertical rows of apparently 
similar cells, more cells being in a row at the center of the sorus 


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B 
Fic. 2. A, section showing part of a telial sorus of Puccinia pallescens, with 
adjoining host tissues; B, a teliospore of P. phakopsoroides treated with eosin to show 
the outer hygroscopic layer of the spore-wall. 625 diameters. 
than at the edge. In Puccinia each row of cells forms a single 
spore; in Phakopsora there are as many independent spores as 
there are cells. In P. phakopsoroides this resemblance is em- 
phasized when the sections are treated with potassic hydrate, and 
the spores pressed out of the sorus (Fic. 1B). The cells then seem 
