104 
Notes on Recent Literature. 
Pritchard inclines rather to the view that infection is carried 
from year to year mainly by means of infected seed. He points 
out that teleutospore pustules of Puccinia graminis are of frequent 
occurrence on wheat grains, and he brings forward evidence that 
fragments of living mycelium are to be found in such grains in the 
cells of the scutellum close to the growing point. It is obviously 
difficult to determine what this mycelium is, but the possibility of 
it belonging to Puccinia graminis must be considered. Pritchard 
supposes that this mycelium invades the embryo at the time of 
germination and thereby causes the infection of the young plant. 
In a second paper the same author 1 gives the results of a 
further investigation of the same problem. Rusted wheat grains 
and their seedlings were microtomed and examined for the purpose 
of tracing the mycelium previously mentioned. Pritchard 
has no doubt that the mycelium found in the young roots and 
stems of such seedlings belongs to Puccinia graminis and that it 
has been derived from the mycelium associated with the spore 
pustules in the pericarp of the grains. This mycelium passes 
upwards mainly in the spaces between the leaf sheaths, though 
branches pass also into the tissues. The nuclei of the hyphae 
are generally associated in pairs, a feature agreeing with the 
nuclear characters of the mycelium of Puccinia graminis. 
The author made no attempt to follow this mycelium onwards 
until the time of spore formation. This would have been a 
laborious undertaking, but the results obtained from it would have 
been of great interest and would have made, perhaps, the evidence 
even stronger than that now brought forward. All the plants used 
in the experiments were fixed for microscopic investigation when 
they were about 10 inches high, and so none were left for the 
investigator to see at what date, if at all, uredo pustules developed 
upon them. 
The proposition brought forward by Pritchard is more tangible 
than Eriksson’s well-known mycoplasm hypothesis, and it is 
certainly the best evidence we have yet that the earliest outbreaks 
of black rust in the year are due to contaminated seed. 
The Biology of the Uredinales. 
An interesting commentary on recent work in this group of 
fungi appears from the pen of R. Mai re. 2 The cytology and sys¬ 
tematic position of the group are first discussed. In regard to the 
origin of the Uredinales, Maire considers that they have come 
from the same stock as the rest of the Basidiomycetes, and 
thinks that this common origin is to be sought amongst the 
ancestors of the Ascomycetes. 
In his classification of the group from the standpoint of general 
life-history, Maire ceases to use the term “ Lepto ” as applied to 
certain forms. The Uredines, whose only functional spore form is 
the teleutospore, were formerly divided into two groups, the Lepto- 
forms whose spores germinated immediately after formation, and 
the Micro-forms whose spores germinated only after a period of 
1 Pritchard, F. J. Phytopathology, 1911, Vol. 1, p. 150. 
2 Maire, R. Prog. Rei Bot. 1911 Vol. 4, p. 109. 
