522 Wisconsin Academy of Sciences, Arts, and Letters. 
malvacearum Mont-., Puccinia adoxae D C., Uromyces scillaA'um 
Wint., and Uromyces ficariae Lev., they were unable to deter¬ 
mine the origin of the binucleated phase. It was found that 
binucleated vegetative cells were present in the mycelium. 
These were found at some distance from the place of spore for¬ 
mation in the case of Puccinia adoxae and Uromyces scillarum. 
In the case of Melampsora rostrupi Wagn., no nuclear migra¬ 
tion was observed, but definite evidence was obtained that the 
binucleated condition had its origin in the fusion of apparently 
equal fertile cells, as I have described for Phragmidium speci- 
osum, Caeoma nitens and Uromyces caladii. 
Blackman and Fraser thus accept the existence of two kinds 
of fertilization processes in the rusts, and believe that in both 
cases the large fertile cells are egg cells which were formerly 
fertilized by male cells (spermatia). This fertilization hav¬ 
ing been abandoned, the egg is fertilized in the one case 
by the nucleus of a vegetative cell and in the other by fusing 
with another egg cell. They regard as of little significance 
Bichards’ suggestion that the true egg was originally, at least, 
a single deep-lying cell, with a long trichogyne, which grew 
after fertilization into the carpogonial branch. Still it is quite 
possible that the uncertainties of such a fertilization might re¬ 
sult first in parthenogenesis, and then in the development of 
a new method of fertilization by a fusion of carpogonial cells. 
The fusion of equal cells would then probably be the more 
primitive process, and the migration of nuclei from vegetative 
to fertile cells would be a later development in such cases as, 
for example, Uromyces poae, where the fertile cells are in less 
regular order than in the caeoma, and perhaps in closer prox¬ 
imity to vegetative cells than to one another. On the other 
hand, the nuclear migrations might have constituted a step in 
the development of a true fusion of carpogonial cells. The dif¬ 
ficulty with all such reasoning is that the evidence for the exist¬ 
ence of Bichards’ carpogonial branch, is hardly satisfactory. 
Blackman’s assumption that the “sterile cell” is a reduced trich¬ 
ogyne is hardly more convincing. The persistence and ap¬ 
parently normal development of the spermatia is also a fact to 
