44§ 
Pole Evans . — The Cereal Rusts. 
Nuclei. 
The nuclei closely resemble those of P. Symphyti-Bromorum , simplex , 
and coronifera , and are usually of an oval shape, and in the vegetative 
hyphae they all divide by the direct method of division. Two such nuclei 
are shown in Fig. 12. 
Haustoria. 
The haustoria of this form, both in the earliest stages of development 
and when they reach maturity, bear very striking resemblances to those of 
P. Symphyti-Bromorum as figured by Marshall Ward ( 33 ). This is 
especially noteworthy, because Eriksson (' 04 ) ( 15 ) in his last paper on 
‘ The vegetative life of the Cereal Rust Fungi ’ expressly states that ‘ In no 
single case has he found such young stages of haustoria as those figured by 
Marshall Ward ’ ( 33 ). 
Consequently I have thought it advisable to show that such stages of 
young haustoria are to be found in this form (P. Phlei-pratensis). See 
Figs. 8, 9, and 10. 
Haustoria are produced from the apices of the hyphae. 
Before a haustorium is formed the hypha becomes distinctly swollen 
to a distance of about ion from the extreme tip. This swollen portion 
becomes cut off by a transverse wall, and contains a protoplasm which is 
more vacuolar than that of the rest of the hyphae. 
In it two or more nuclei of much smaller size than those in the hyphae 
are seen. 
Simultaneously with the transverse wall which cuts off the haustorium, 
a tube-like structure begins to grow out and pierce the host cell-wall. 
After penetrating the wall, the little tube then begins to swell at its distal 
end, and very soon a brightly staining granule is seen in its interior, and 
this generally lies near the aperture of the tube. 
As the body of the haustorium increases in size, its proximal swollen 
end becomes quite empty, and the small round nuclei which were present 
in it are now seen to have passed over into the distal end of the haustorium 
(Fig. 11). The large haustorium embracing the host cells nucleus in 
Fig. 11 is the form commonly seen in the chlorophyll containing cells, 
while the small hammer-headed forms are rather common in the epidermis. 
Puccini a Glumarum (Schmidt), Erikss. and Henn. 
This is the Yellow rust of wheat, by far the most prevalent of rusts on 
the wheat fields around Cambridge. In South Africa as yet I have not 
found this rust, and doubt whether it exists here. 
It was originally included under P. ruhigo-vera , DC. (P. striaeformis , 
Westd., and P. straminis , Fuck.). 
