236 BOTANICAL GAZETTE [SEPTEMBER 
from A. pastoralis and A. flexicaulis are alike in infecting capacity, except that 
conidia from the former will only partially infect A. pubescens, and not A. alpigena 
at all; while conidia from A. flexicaulis partially infect A. alpigena, A. pubescens 
being entirely immune. Another case is that of the mildew on A. impexa which 
does not infect A. alpina vera or A. nitida, while conidia from A. pastoralis par- 
tially infect these hosts. Otherwise the two mildews are alike. STEINER further 
found that conidia from species of the Vulgares group will not produce full infec- 
tion on alpine species, although conidia from alpine species produce full infection 
on the Vulgares species. STEINER supposes that the mildew on the alpine species 
came originally from Vulgares species and is only partially adapted to the ete 
osts. He also believes that the appearance of the mildew on alpine species 1S 
due to unfavorable environment. me 
STEINER also claims to have found “‘bridging species;” for example, conidia 
from A. nitida infect A. impexa but not A. fallax, while conidia from A. 1mpexd 
will infect A. fallax. Thus the mildew is carried over from A. nitida to A. jallae 
through A. impexa. Similarly, A. pastoralis and A. impexa transfer the mildew 
from A. connivens and A. pubescens to A. micans. In addition to the fact that 
only a few tests were made, STEINER does not tell us what are the infecting powe™ 
of the mildews produced in this way on A. micans and A. fallax. 
His conclusions would be more convincing if based on a larger number of tests. 
A large number of foreign infections also occurred in his experiments, no less tha 
71 foreign infections occurring in a total of 380 tests. The results are presented 
very clearly by means of a series of well-devised diagrams.—GEorGE M. REED. 
Cytology of Florideae.—Cytological studies on the Florideae have ge 
comparatively rare, partly on account of the difficulty in securing material, bu 
principally on account of the difficult technic. Quite recently KursSANOW es 
publisheds the results of his studies on three different forms of red algae: ue 
minthora divaricata, Nemalion lubricum, and Helminthocladia purpurea. ue 
investigations did not deal with nuclear details, but rather with the morphology ° 
fertilization of the carpogonium, the development of carpospores, and the aes 
of the chromatophores. : : 
He failed to find a nucleus in the trichogyne of Nemalion and iceman 
the trichogyne in these forms seems to be an extension of the carpogonium. 
believes that such a condition is found only in the simplest forms of red srt 
and agrees with the reviewer that a trichogyne with a nucleus, and yet W! 6 ; 
a partition wall between it and a carpogonium, as in Polysiphonia, may The 
forerunner of the multicellular trichogyne found in the Laboulbeniaceae- : 
spermatium (sperm) has a single nucleus, agreeing with the reviewer's ages 
tion of Polysiphonia. He thinks that a uninuclear condition in the spet™ ults 
perhaps be universal in red algae. In Nemalion, contrary to WOLFE’S Tes 
the chromatophore has, in its center, a well-formed pyrenoid which is com 
; 473-330" 
5 Kurssanow, L., Beitrige zur Cytologie der Florideen. Flora 99331133 
pls. 2, 3. Ig09. 
