4 54 
Pole Evans . — The Cereal Rusts. 
The hyphae from now onwards become extremely thin (Figs. 20 and 
21), from 3-5-6 fx in thickness, and always have a great tendency to make 
for the stomatal cavities. Here they branch very rapidly, forming a dense 
weft, giving rise to the Uredo sori, which are seen bulging out the cells in 
the region of the stomata. 
Puccinia dispersa , Erikss. 
This is the Brown rust of the rye, originally included under the old 
P. c Rubigo-vera ’ (DC.), as Aecidium asperifolii , Pers. 
Eriksson ( 9 ) was the first to point out the characteristics of the 
‘ Braunrost ’ (P. dispersa , Erikss. and Henn.), and very soon afterwards 
he split it up into the specialized forms (f. sp. Secalis , Tritici , Bromi , 
Agropyri). 
Later on Eriksson ( 11 ) showed that the brown rust of the rye 
P. dispersa , Erikss. (not Erikss. and Henn.), is a distinct species from the 
other brown rusts, for its uredo and teleutospores are only found on Secale 
cereale , L., and JS*. montanum , Guss., not on Triticum , & c. 
The aecidium is found only on Anchusa arvensis and A. officinalis. 
The teleutospores are capable of germination immediately after their 
formation, and as was shown by Eriksson and confirmed by Klebahn (22), 
when the teleutospores from Secale cereale are sown on Anchusa arvensis 
and A. officinalis the aecidia are always produced, whereas sowings of the 
teleutospores from Triticum vidgare , Bromus mollis , Bromus macros tacky s 
failed to produce the aecidia on Anchusa. The aecidiospores from Anchusa 
arvensis and A. officinalis always successfully infected Secale cereale , but 
these aecidiospores when sown on Triticum vidgare , Bromus arvensis, 
Hordeum vulgare, A vena sativa, Agropyrum repens , Ho tens lanatus produced 
no results. 
Also uredospores from Secale cereale would only successfully infect 
Secale cereale , but failed when sown on Triticum vulgare , Bromus mollis , 
Bromus arvensis , Agropyrum repens , Holcus lanatus, Trisetum flavescens, to 
produce the Uredo pustule. 
In the field the uredo stage is distinguished by the pustules being 
from 1 to 1-5 mm. long, nearly 1 mm. broad, and scattered irregularly over 
the leaf. Asa rule the pustules are of a Terra Sienna colour (but too much 
reliance must not be placed on colour). 
The spores are usually round, spinous, of a dirty yellow, and measure 
in diameter 19-20 fi. 
The Histology of Uredo dtspersa, Erikss. 
The general development of the mycelium of P. dispersa is very 
similar to that of P. glumarum and P. Symphyti-Bromorum. and the other 
species to be described. 
