320 BOTANICAL GAZETTE [APRIL 
VERNON H. BLACKMAN has published a preliminary notice of the 
results of his study of the Uredineae, the full paper, with figures, to appear 
later in the Annals of Botany. The forms studied were Phragmidium 
violaceum Wint. and Gymmnosporangium clavariaeforme Rees. Sapin- 
rouffy’s cycle of nuclear development was confirmed, which is as follows: 
the mature teleutospore is uninucleate and this condition persists through 
sporidia and the aecidial mycelium; in the young aecidium the nuclei become 
paired, and this condition persists through aecidiospores, the ensuing mycelium, 
the uredospores, and into the young teleutospores; in the maturing teleuto- 
spores the two nuclei fuse. It was this fusion in the teleutospore that Sapin- 
Trouffy regarded as fertilization. 
lackman concludes that the spermatia are male cells that have become 
functionless, basing his conclusions upon the cytological characters, which are 
clearly those of male cells and not of conidia. The aecidium of P. violaceum 
arises as a layer of rectangular uninucleate cells just beneath the epidermis 
of the leaf, Each of these cells becomes divided into a short sterile cell above, 
which soon degenerates, and a fertile cell below, which becomes binucleate 
and gives origin to a row of binucleate aecidiospore mother-cells. Thus the 
condition of paired nuclei starts in the fertile cell and is continued to the 
teleutospore. The fertile cell, which the author regards as a female cell, 
does not become binucleate by division of its original single nucleus, but by 
the migration through the walls of the nucleus of a neighboring vegetative 
cell. This association of the two nuclei he regards as representing fertiliza- 
tion, rather than the act of fusion in the teleutospore. 
This means a sharply marked alternation of generations among the 
Uredineae. The gametophyte starts with the uninucleate teleutospore, the 
production of the four sporidia representing a tetrad division; from these the 
mycelium of the gametophyte develops and produces later the spermogonia 
and aecidia, The fertilized cell in the aecidium starts the sporophyte genera- 
tion with paired nuclei, from which the aecidiospores almost immediately 
arise; the sporophyte mycelium bears. later uredospores and finally teleuto- 
spores. The fusion of nuclei in the teleutospore cannot then be looked upon 
as a process of fertilization, but merely as the secondary process which brings 
about the disappearance of the special cytological conditions initiated by fer- 
tilization, 7. ¢., change from the sporophytic to the gametophytic condition; 
it must accordingly be looked upon as a reduction process. Like the reduc- 
tion process in higher plants, it is followed by a tetrad division. These con- 
clusions apply also to the fusion of nuclei in the basidium, as Maire has 
shown that Basidiomycetes also have paired nuclei that fuse in the basidium. 
Just how the fusion of sexual and vegetative nuclei is to be regarded as 
fertilization is not clear, but such cases loosen up the previous rigidity of 
BLACKMAN, VERNON H., On the fertilization, alternation of generations, and 
general cytology of the Uredineae. Preliminary notice. New Phytologist 3:23-27- 
1904. 
