352 Blackman. — On the Fertilization , Alternation of 
ignorance of the origin of the two nuclei and the exaltation of nuclear fusion 
as a test of fertilization. The fusion is the result of a sexual process (at 
least in Phrag. violaceum ), but is clearly not in itself a fertilization. 
Raciborski (44), when he put forward the hypothesis that the conjugate 
divisions in the Uredineae represented a vegetative phase intercalated 
in fertilization between the stages of cytoplasmic fusion and nuclear fusion, 
was much nearer the truth, though, as has been pointed out above, it is not at 
all necessary to consider nuclear fusion as a stage in fertilization as usually 
understood. Raciborski, equally with Dangeard and Sapin-Trouffy, was 
quite ignorant as to the method by which the two nuclei became ‘ conjugate.’ 
Maire (29) had earlier recognized a similarity between the conjugate 
nuclei of the developing egg of Cyclops and the paired nuclei of the 
Uredineae, and applied the term ‘synkaryon 5 to the two nuclei. He 
recognized that the fusion in the teleutospore was not in itself a process of 
fertilization, but considered it a mere process of ‘ mixie,’ in which he 
includes both nuclear and chromosome reduction in the sense used above. 
He believed the ‘ synkaryon ’ to be brought about by the association of 
two daughter-nuclei of a cell, and at first considered it actually comparable 
to a sexual process, but in a later paper (30) he comes to the conclusion 
that between the fertilization in the higher plants and the formation of 
the ‘ synkaryon ’ in Uredineae (and Basidiomycetes generally) there are only 
* des relations de cousinage.’ He elaborated his views in some considerable 
detail, but the discovery of the origin of the two nuclei in the aecidium of 
Phragmidium , and the evidence here brought forward that the spermogonia 
and aecidia are in all cases to be considered as sexual organs, throws 
a completely new light upon the matter ; his views need not therefore be 
discussed further. 
ORIGIN OF THE PROCESS OF FERTILIZATION. 
The process of fertilization as observed in the fertile cells of Phrag. 
violaceum might be looked upon as merely one of great simplicity in which 
the male cell remained undifferentiated. The two nuclei which take part 
in the process are not sister-nuclei though they may sometimes be closely 
related, and the process as a whole (except for the absence of obvious 
cytoplasmic fusion) is not much simpler that that of Basidiobolus , in which 
two neighbouring cells, after forming each a sterile cell, fuse together to 
form a zygospore. 
Taking into account, however, on the one hand, the completely un- 
differentiated nature of the cell from which the acting male nucleus comes, 
and the peculiar method by which the nucleus passes from one cell to another, 
and on the other, the presence of the functionless spermatia with their 
special cytological characters, the only view that seems satisfactory to 
explain the facts is that the primitive normal process of fertilization by 
