1922] CURRENT LITERATURE 339 
White pine blister rust.—The present state of our knowledge concerning 
this most important tree rust is ably summarized by SPAULDING? in a recent 
contribution from the Bureau of Plant Industry. The extensive scope of the 
treatment is partially indicated by the bibliography of 180 titles. The opinion 
is expressed that Cronartium ribicola is of Asiatic origin, that it spread through- 
out Europe during the nineteenth century, and was introduced into North 
America on young trees of Pinus Strobus after 1900. The life history of the 
fungus and its relations with its various hosts are exhaustively discussed. It is 
regarded as established that the overwintering is chiefly by the mycelium in the 
bark of living pines, and that it is in this stage that the long migrations have 
taken place, but it is also recognized that the fungus may overwinter on Ribes. 
The attempts which have been made to control the disease are reviewed, and 
the conclusion is reached that its eradication is impossible except in the case 
of small isolated advance infections, but that the systematic removal of all 
Ribes in white pine forest areas will kee i the disease in check, and that this 
method is both practicable and profita 
Eriksson’ renews his contention a the Peridermiums on Pinus Strobus, 
P. silvestris, and P. Cembra are biological races of a single species in which the 
specialization is not yet definitely fixed. He believes that he has evidence that 
the white pine blister rust is transmitted by diseased seed and also from pine 
to pine. The direct evidence presented is not of the sort that can be regarded 
as final. To supplement it, so far as the matter of the spread from pine to pine 
is concerned, great emphasis is laid upon the undoubted autoecism of closely 
related species, veh foo stress upon the results of Haack. These, it is 
interesting to note, are characterized as worthless by SpauLpiING. The latter 
admits, however, that the ks of MEINECKE and of Hepccock on Peridermium 
cerebrum, and that of KLEBAHN on Peridermium pini “throw doubt on the 
strict heteroecism of the aeciospores of all stem-inhabiting pine Peridermiums.”’ 
This is very far from proving the autoecism of the aecidiospores of Peridermium 
strobi, as ERIKSSON seems to assume. The point is obviously one of funda- 
mental importance, and it is to be hoped that the experiments now under way 
in this country will shortly throw more light upon it. ERrKsson finds in recent 
American and European experiences of the overwintering of the fungus on Ribes 
a complete justification of his own early expressed belief concerning this phase 
of the problem. That such overwintering occurs cannot longer be doubted. 
That it is of any great penta in the perpetuation of the disease is still very 
questionable.—G. W. Mar 
soetes.—OsBoRN? has obtained some very interesting results from an 
investigation of Isoetes Drummondii, a species widely distributed in certain 
7 SPA G, Perey, Investigations - sy white pine blister rust. Bull. 957. 
US. Dene A Aare. Pp. roo. eet 6. figs. 13. 
RIKSSON, JAKos, connection oe Peridermium strobi Kleb. and one 
posable ribcle Dietr., is it boobs ornot? Acritical review. Arkiv Botanik 18:1 
gs. 6. 
Oe , T. G. B., Some observations on Isoetes Drummondii A. Br. Ann. 
Botany 36: 41-54. figs. 15. 1922. 
