45 ° 
Pole Evans.- — The Cereal Rusts. 
always the case, for frequently the Fungus will invade a leaf from an 
infected area in the most methodical fashion, e. g. it will spread uniformly 
through the leaf blade both up and down the leaf from an infected area at 
the rate of 10-12 mm. per day. that is to say the total length of leaf 
infected per day usually amounts to 20-24 mm. 
The pustules are always much more numerous on the inner face of the 
leaves than the outer. 
They are from *5-1 mm. long and -3—4 mm. broad. 
The spores are round or shortly elliptical echinulate and yellow, 
measuring 25-30 1* in diameter. 
The uredospores are easily distinguished under the microscope through 
their colourless membrane from the spores of the Brown rust with its 
brownish coloured membrane. 
An aecidium of P. glumarum has so far not yet been discovered, and 
this is not by any means surprising, for very few trials appear to have been 
made in this direction. 
Eriksson, it is true, has tried to infect with the teleutospores (which 
like those of P. dispersa germinate directly they are ripe) Anchusa awe ns is, 
officinalis , vulgaris , Cynoglossum officinale , and Pidmondria officinalis , but 
with no success. 
Around Cambridge the Uredo pustules are to be found all the year 
round, both on the side tillers in the unploughed stubble fields and also on 
the fields of young winter corn. It should be mentioned that especially 
during the months of January and February it is those leaves of the winter 
corn which lie or come into contact with the damp soil that are very liable 
to show the uredo pustules and characteristic yellow flecks. 
The Histology of Uredo glumarum. 
The following works dealing more or less with the histology of 
P. glumarum have already appeared: — 
Eriksson and Henning ( 17 ) gave a short description of the anatomy of 
the Yellow Rust with a few figures. 
Klebahn ( 24 ) in a short article on 'The anatomy of the Yellow Rust’ 
drew attention to the great thickness of the hyphae in this species when com- 
pared with those of the other cereal rusts. He also suggested that Eriksson 
had probably mistaken the haustoria of these rusts for his ‘ mycoplasm.’ 
In January, 1904, Eriksson and Tischler ( 18 ) published as the first of 
a series of articles ‘ Uber das vegetative Leben der Getreiderostpilze ’ a paper 
on ‘ Puccinia glumarum (Schm.), Eriks, and Henn., in der heranwachsenden 
Weizenplanze ’. 
This paper deals with the mycoplarm hypothesis. Both normal and 
abnormal hyphae are figured, and Eriksson maintains that one is only a stage 
in the development of the other. 
