394 



FUNGOUS DISEASES OF PLANTS 



larger branch cutting off an apical cell. The smaller gamete in 

 time loses its nucleus by migration through a pore into the larger 

 gamete, and the cells thus provided with two nuclei become each 

 properly the basal cell of one of the chains of spores which arise 

 in this type, corresponding to the aecidium, each spore of which 



J. 



FIG. 194. PHRAGMIDIUM SPECIOSUM: DEVELOPMENT OF ^CIDIOSPORES 

 (After Christman) 



a, progametes ; &, gamete and sterile cell ; c, after gametic fusion and nuclear 

 division ; d and e, spore production 



possesses paired nuclei. He would also homologize the apical cell 

 of the larger gamete with the trichogyne of certain lower plants, and 

 would assume that in the phylogeny of these plants the spermatia 

 were functionally in connection with this organ. The work of 

 Christman and Olive on this and other rust fungi in part confirm 

 Blackman's results. They are also able to identify the gametes, but 

 the communication between these two adjacent cells is generally. 



