86 BOTANICAL GAZETTE [august 



JMaire in his general conclusions regarding the chromatin fusion and 

 reduction in the maturing and germination of the teleutospore* He 



further believos that the entrance of the vegetative nucleus is to be 

 interpreted as a fertilization, though describing it as a '^reduced fer- 

 tilization" which has replaced a former fertilization by a true male 

 cell — the spermatium. 



Shortly after the appearance of Blackman's paper, I described 

 (5) a true fertilization in a somewhat similar form — Phragmidium 

 speciosiim Fr. The method of union of the two cells was found to be 

 decidedly different. The cells combining are of approximately equal 

 size, as are also their nuclei. Two such cells come together at some 



point on their adjacent walls. A considerable portion of the walls 

 in contact dissolves away and the two protoplasts fuse. This large 

 structure now elongates and from its apex a row of spores is abstricted 

 (fig. i8). The same general behavior of the cells was found to occur 

 in the aecidium of Uromyces caladii. Here, however, the cell pro- 

 duced by the fusion of the gametes elongates to a greater extent than 

 in Phragmidium speciosum, and the two nuclei wander out into the 

 elongated portion and remain there during spore-formation. The 

 two bases of the gametes are often nearly obliterated. On the basis 

 of these facts it was suggested that the rusts were after all more closely 

 related to the lower fungi than to the red algae and ascomycetes. 

 Certainly the union of the two cells is very like the zygospore forma- 

 tion common in the lower forms. 



Blackman and Fraser (3) in 1906 confirmed Blackman's pre- 

 vious observations on nuclear migration, this time working on the 

 aecidium of Uromyces poae Rab. As described for Phrag, violaceum, 

 they found that the nucleus migrates through the cell wall. Similar 

 migrations were found in the aecidium of Puccinia poarum Niels. 



In the aecidium oi Melampsora Rostriipi Wagn., distinct evidences 

 were obtained of the fusion of two large equal cells. In Puccinia 

 malvaceanim !Mont., Puccinia adoxae DC, Uromyces scillarum Wint., 

 and Uromyces jicariae Lev., BLACKMANVas unable to locate the origin 

 of the binucleatcd phase. He suggests that a nuclear migration 

 occurs in the hyphae some time between the infection with sporidia 

 and aecidiospore-formation. 



Still later (1907) I have described (6) a fusion of cells similar to 



