1915] CURRENT LITERATURE 419 
Wherein lie the causes of this peculiar difference of behavior of the two kinds 
of buds the author was unable thus far to determine. 
HAAK" has published a somewhat lengthy account of a series of general 
observations and experiments on the biology of Peridermium Pini, and particu- 
larly on the question of the propagation of this rust by aecidiospores. From 
the observation that no probable telial host is coextensive in its distribution 
with Pinus sylvestris and its blister rust (Peridermium Pini), and also because 
of the failure up to this time to find the telial phase of this rust, Haak infers 
the likelihood that this fungus is propagated on the pine by aecidiospores. 
This assumption contains in itself nothing anomalous, since several rusts with 
repeated aecidial generations are known. The experiments by which it is 
endeavored to substantiate this assumption furnish only probable evidence. 
Cultures on sound trees having failed to give satisfactory results (out of 72 
trees with about 200 sowings only one infection resulted), subsequent cultures 
were made only on trees which showed the presence of Peridermium. The 
diseased branches were removed and numerous small twigs were infected in 
wounds. Although the number of Peridermium cankers resulting from these 
infections was small compared with the number of infected twigs, the proportion 
of diseased twigs to sound twigs was much greater on the infected branches 
than on the uninfected ones. The circumstantial evidence, therefore, seems 
to indicate that this fungus can be propagated on the pine by means of aecidio- 
spores. A histological examination to determine whether the mycelium under 
the aecidia was sporophytic or gametophytic was not made. Two further 
points of interest in the biology of this fungus are brought out by the author. 
First, natural infections take place only in green twigs still bearing needles; 
no infections occur in older twigs. Even old cankers on trunks and large 
branches, where the origin has not been completely obliterated, can be traced 
to infections of small twigs from which the disease has gradually spread. 
Secondly, when a tree is once infected, the disease spreads by new infections 
to other branches during succeeding years. This fact is in accord with the 
theory that the aecidiospores are capable of reinfecting the pine. 
Baupys” adds a contribution to the question of the maintainance of rusts 
by means of wintering uredospores or mycelium. The observations were made 
during the winters of 1910-1911 and 19} 1-1912 in Bohemia, where the tempera- 
ture ranged as low as — 16° C. and —21° C. respectively during the two seasons. 
From 60 to 100 per cent of the uredospores in the winter sori of Puccinia 
glumarum and P. dispersa on rye, and P. bromina on Bromus sterilis were found 
to retain their capacity for germination throughout the winter. These rusts 
« Haak, ———., Der Keinzopf Peridermium Pini (Willd.) Kleb. Zeitschr. 
Forst u. ‘Hiddeenen we 3-46. pis. 2. 1914. 
” Baupys, E., Ein Beitrag zur Uberwinterung der Rostpilze durch Uredo. Ann. 
Mycol. 114:30-43. 1913. 
