No. 460.] STUDIES. ON PLANT CELL. —VF. 249 
binucleate is one of the most interesting problems in this field of 
botany. This is the point where we should expect to find the 
remains of sexual organs, if any are present in the higher 
Basidiomycetes, but it is not likely that they will be found. It 
seems more probable that the mycelium with the paired nuclei 
(perhaps sporophytic in character) arises apogamously with a 
complete suppression of the sexual organs in agreement with such 
of the Uredinales as have no zecidium and the Ustilaginales. 
Blackman's explanation of the history of the paired nuclei in 
Phragmidium is full of interest. As stated before, he regards 
the fertile cell which develops a chain of zcidiospores, “as a 
female reproductive cell which undergoes a process of fertiliza- 
tion" by a union with an adjacent cell of the mycelium and its 
reception therefrom of a nucleus. The mycelium then which 
arises with the zcidiospore is sporophytic in character and so 
remains until the fusion of the pairs of nuclei in the teleuto- 
spores. The male organs of the rusts are the spermogonia and 
the male gametes the spermatia which are of course now func- 
tionless so that the “process of fertilization" is through the 
introduction into the female cell of a nucleus which is not phy- 
logenetically a male sexual element. Blackman’s (:04a, pp. 
349—353; :04 b) conception of the process as an act of ferti- 
lization involves some principles which will be briefly outlined. 
Blackman believes for Phragmidium “ that the primitive normal 
process of fertilization by means of spermatia has been replaced 
by fertilization of the female cell through the nucleus of an 
ordinary vegetative cell " and regards the process as very similar 
to the phenomenon reported in the apogamous development of 
ferns by Farmer, Moore, and Digby (:03), which will be consid- 
ered presently. Blackman points out that normal processes of 
fertilization such as we have included under the head of ‘sexual 
cell unions and nuclear fusions" do not involve in many forms 
(probably all types with a sporophyte generation) an immediate 
union of the chromatin of the sexual nuclei which is known to 
remain distinct during the first cleavage mitosis in a number of 
types (e. g., Pinus and some other gymnosperms). So there is 
nothing in the delayed fusion of the paired nuclei up to the 
teleutospore that is seriously against his explanation of the “ fer- 
