136 MORPHOLOGY OF GYMNOSPERMS 



A ventral canal cell in cycads was first described by Strasbukger 

 (7) in 1876 for Cycas sphaerica, and the next year Warming (8) 

 described one in Ceratozamia rohusta, but soon concluded that he 

 had been mistaken. Treub (13) in 1884 failed to find any ventral 

 canal cell in Cycas circinalis, and from that time it was generally 

 believed that the cycads have no ventral canal cell. In 1898, however, 

 Ikeno (27) made an unmistakable demonstration of the critical 



Figs. 145-147. — The ventral nucleus in cycads: fig. 145, Cycas revoluta; mitosis 

 which produces ventral canal nucleus and egg nucleus; X375; fig. 146, Dioon edule; 

 later stage, showing that no cell plate is appearing in connection with the spindle; 

 X350; fig. 147, Dioon edule; the ventral canal nucleus disorganizing, while the egg 

 nucleus is increasing in size (no waU has been formed between the nuclei); X41. — ■ 

 Fig. 145, 3-f'si' Ikeno (27); figs. 146, 147, after Chamberlain (46). 



mitosis in Cycas revoluta (fig. 145), his figures showing that no wall 

 is formed. Webber (26) in 1897 reported a small cell cut off from 

 the apex of the archegoniimi in Zamia, but in 1903 Coulter and 

 Chamberlain (33) showed that here too there is only a nuclear 

 division. Later Chamberlain (46, Ceratozamia, Stangeria) showed 

 that there is a ventral canal nucleus in Dioon, Encephalartos, 

 Ceratozamia, and Stangeria (figs. 146, 147). The figure of Dioon 

 shows not only that there is a nuclear division that gives rise to the 

 ventral canal nucleus and egg nucleus, but also that wall-formation 

 between the two nuclei has been so completely suppressed that no 

 trace of its initiation is seen in the spindle. 



