CYCADALES 



25 



to represent the vegetative tissue of the gametophyte it is often 

 called a " prothallial cell." There is no evidence from the lit- 

 erature or plates re- 



ferred to above that 

 an evanescent vegeta- 

 tive cell precedes the 

 persistent one, al- 

 though the occurrence 

 of such a cell is possi- 

 ble, and it should be 

 looked for. At this 

 early stage, therefore, 

 the male gametophyte 

 consists of a single 

 small vegetative cell 

 and a large cell which 

 we regard as the an- 

 theridium initial. The 

 latter cell divides un- 

 equally, and a second 

 small cell is organized 

 which is in contact 

 with the vegetative 

 cell. This division dif- 

 ferentiates the sterile 

 and the fertile series 

 of the antheridium. 

 The larger, or sterile 

 cell, seems to repre- 



P'S. . 



A 



FiQ. 23. — Zamia integrifolia : A^ pollen tube, show- 

 ing remnant of pollen grain (pg), stalk cell (s), 

 body cell (J), vegetative cell {v), and tube nucleus 

 (t), y. &0\ B, the body cell represented in J, show- 

 ing the two blepharoplasts (c) surrounded by radia- 

 tions, X 366 ; C, division of body cell, showing the 

 two immature male cells and the fragmented bleph- 

 aroplasts (c), X 133. — After Webber. 



sent the antheridial 

 wall, but since its chief function is to develop the pollen 

 tube it may be called the tube cell, and its nucleus the tube 

 nucleus. These are the " vegetative cell " and the " vegeta- 

 tive nucleus " of ordinary terminology, but these phrases are 

 more applicable to the so-called " prothallial cell " and its 

 nucleus. 



The smaller cell formed by the division of the antheridial 

 initial is the 'primary spermatogenous cell, called in botanical 

 literature either the generative cell or " antheridial cell." Web- 

 ber has observed in Zamia an interesting relation between the 



