CONIFERALES 



311 



Just what the stalk cell really is, no one has determined definitely. 

 Where it does not have the stalk position, as in Araucaria and 

 others, the stalk and body cells, at first, look alike, and probably 



Fig. 313. — Araucaria cunninghamii: male gametophyte: in A-C, the first primary 

 prothallial cell has not divided; in D, it is dividing periclinally; in E-II, it has divided 

 anticlinally; /, shows an unusually large number of prothallial cells; t, tube nucleus; g, 

 generative cell; s, stalk cell; b, body cell; X900. 



neither is predestined to become the "body cell" and produce the 

 two gametes. In Microcycas, Dr. Dorothy Downie^" found that 

 the stalk cell divides repeatedly, each time cutting off a body cell, 

 which later produces two gametes. In this case, the stalk cell is 

 spermatogenous. In conifers, it may be, phylogenetically, a sperma- 

 togenous cell, like the body cell. 



