ON GRAMINEZ 265 
On leaves and culms of Hordewm vulgare and other species 
of Hordeum. Teleutospores, August, September. (Fig. 202.) 
The Dwarf Brown Rust of Barley, distinguished by the fact that it 
bears few two-celled teleutospores, but very numerous mesospores, which 
are variable and asymmetrical, slightly thickened at the apex (46), 
measuring 25—45x16—24p. It is to be found in the uredo-stage all the 
year round. The teleutospores germinate in spring; Klebahn tried to 
infect, with their basidiospores, the same forty-two species which he 
tested with P. triticina, but equally in vain. 
009 
Fig. 202. P. simplex. Teleutospores. 
P. simplex may be worthy of being regarded as a distinct species ; it 
presents a little more difference from the other forms of P. dispersa than 
they do from one another. The sori of both kinds are amphigenous and 
more minute and punctiform (except on the culms), and the uredospores 
are of a brighter yellow. On Hordeum distichum I have found sori of 
P. simplex on the leaves, and with them those of P. graminis on the culms, 
It will: be noticed that all the last five races are without 
any known ecidium; it follows, apparently, that they must 
maintain themselves by their uredospores, but one might 
venture to suggest that future, unexpected, discoveries will 
throw light upon this obscure matter. Eriksson and Klebahn 
have both proved, by numerous infection experiments, that 
these races or subspecies of P. dispersa are all biologically 
distinct ; with few, and doubtful, exceptions none of them can 
be transferred from its own to the other hosts. 
There are other forms of Brown Rust of which little is 
known. The ecidium on Lchium vulgare mentioned by Plow- 
right (Ured. p. 168) may belong to one of these; this plant was 
one of the forty-two previously mentioned, tested by Klebahn. 
I have also some specimens of uredospores on Aira flexuosa 
-and A. caespitosa sent by Mr T. B. Roe from Scarborough; those 
