374 BOTANICAL GAZETTE [APRIL 
common orange rust of the blackberry is a short cycle form of the type of 
Endophyllum, needs merely to be mentioned here. The discovery of this rust, 
now known as Kunkelia nitens (Schwein.) Arthur, is a striking illustration of 
the proposition of TRANZSCHEL and of FiscHER, which may be generalized in 
the statement that the aecidial hosts of long cycle rusts often bear short cycle » 
rusts whose teleutospores resemble one of the spore forms of. the long cycle 
rust. 
BARTHOLOMEW®% finds that the mycelium producing the thin-walled spores 
which occur together or separately in the uredinia of the fern rust Hyalopsora 
Polypodii is binucleate throughout, and that there is therefore no reason for 
regarding the two spore forms as other than uredospores. 
A very extensive investigation of the biological forms of Puccinia graminis 
in the area extending from the upper Mississippi valley through the northern 
great plains to the intermountain area of Washington and Idaho has been 
made by STAKMAN and PIEMEISEL.% Uredospores of P. graminis from about 
30 species of grasses in this region were systematically sown on the common 
cereals and a number of other grasses, and in like manner uredospores from the 
cereals were sown on a large number of other grasses. The results of the many 
hundreds of cultures are tabulated in a readily comprehensible form. Six 
biological forms were isolated; of these, one, P. graminis Tritici compacti, is 
new. The others are the fornss formerly distinguished, namely, P. graminis 
Tritici, P. graminis Secalis, P. graminis Avenae, P. graminis Agrostis. The 
extent of this work and the thoroughness with which it was carried out place 
the problem of the differentiation of biological races of Puccinia graminis ina 
much clearer light than has heretofore been accomplished. It is found that 
each biological form attacks a group of grasses not necessarily related. ‘Within 
each group all degrees of susceptibility exist; the range from complete sus- 
ceptibility to complete immunity is therefore gradual. The groups susceptible 
to the various biological races overlap considerably, so that the same grass 
may be host to a number of biological races of rust. Thus barley, rye, an 
Bromus tectorum have been infected by all of the 6 races of P. graminis; while 
oats has been infected by all except P. graminis Tritici compacti. The forms 
can nevertheless be differentiated by means of other grasses which are distinctly 
susceptible to some and immune to others of the biological races. These facts 
will probably explain the apparently different degrees of specialization of the 
orms of P. graminis by observers in different geographical regions. Within 
the region studied by the authors, no geographical specialization was observed. 
—H. HassELBRING. 
3 BARTHOLOMEW, E. T., Shier oer on the fern rust Hyalopsora Polypodit. 
Bull. Torr. Bot. Club petted Sigs. 3. 1913. 
4 STAKMAN, E, C., and nthe F. J., Biologic forms of pions graminis on 
cereals ind princes. Jour ur. Agric. Research 10:429-495. pls. 7. 
