Pole Evans . — The Cereal Rusts , 
461 
The haustoria, especially in the cells bordering on the vascular 
bundles, are of large size and cylindrical in shape. The pin-head type so 
common in the case of IJredo graminis is rarely met with. 
Puccinia Sorghi, Schwein. 
This rust is probably to be found wherever Maize is cultivated. In 
some parts of South Africa considerable damage has been wrought in 
the ‘ Mealie 5 crop through the agency of this parasite ; but as a general 
rule little attention is paid to it. 
Kellerman ( 19 ) has shown that the uredospores of P. Sorghi readily 
infect any and all of the ‘agricultural species’ of Maize, and that Teosinte 
(Euchlaena luxurians) was also a host for this species of rust, but that 
attempts to inoculate Sorghum vulgar e, Saccharum officinarum and Tripticum 
dactyloides failed. 
Recently Arthur ( 1 ) ( 2 ) has shown that this rust is heteroecious on 
Oxalis cymosa , successfully producing the aecidia on Oxalis from the 
teleutospores, and in turn infecting the Maize with the aecidiospores so 
obtained. 
In this country MacOwan, as far back as 1879, found an Aecidium 
in Cape Colony on Oxalis Bozuei , and quite recently I find that Burtt-Davy 
has collected an Aecidium in Swaziland on Oxalis setosa. Whether these 
two act as hosts for P. Sorghi remains to be seen. 
The pustules of Uredo Sorghi are found on both sides of the leaf. 
When they are closely crowded, they frequently run together to form a large 
dark brown erumpent pustule. 
The uredospores are globose, elliptical or ovate, slightly verruculose, 
and measure from 23-30 x 22-25 \i. 
The sub-stomatal vesicle is somewhat triangular in shape when seen 
in longitudinal section (Figs. 40, 43), and gives rise to two or more infecting 
hyphae from the angles of the base. 
In transverse section it is of the form shown in Fig. 43. 
The hyphae are a little more robust than those of the other species 
described above, with the exception of P. glumarum , measuring as a rule 
from 4*5-5 // in diameter. 
The haustoria are frequently branched, as is shown in Fig. 41, and are 
constantly found in contact with, or carefully wrapping round, the nucleus 
of the host cells. 
Summary of Results. 
As the accompanying table will show, these different species of Puccinia , 
in the early stages of development of their Uredo mycelium exhibit 
morphological characters (seen especially in connexion with the formation 
of the sub-stomatal vesicle) which serve at once to distinguish them from 
one another. 
