178 BOTANICAL GAZETTE [September 



Fig. 24. — Showing the stalk (sc) and body (be) cells as well as prothallial 

 cells (p!, p 2 ) and tube nucleus (t). 



Fig. 25. — The mitosis giving rise to stalk and body cells from the primary 

 spermatogenous cell. 



Fig. 26. — A usual type of mature gametophyte, having four derivatives of the 

 first primary prothallial cell (pr), four of the second (p 2 ), stalk (sc), and body (be) 

 cells, and tube nucleus (t); nine cells also usual (two p lf four p a , stalk, body, 

 tube). 



Fig. 27. — Showing the prophase of the division of the first prothallial cell 

 (/>,) and what appears to be a "cell" (x) on the side of the body cell opposite to the 

 stalk cell (sc); no nucleus could be discovered in this "cell;" see text for further 

 details. 



Fig. 28. — Division of the microspore nucleus in P. nivalis; a peculiar seg- 

 mented appearance of the spirem, which has about completed segmentation into 

 chromosomes, is shown. 



Fig. 29. — A similar but younger spirem which has not yet begun to segment 

 as the preceding one has done. 



Fig. 30. — Anaphase of the division resulting in second prothallial cell (p 2 ) 

 and antheridium initial. 



Fig. 31. — Late telophase of division of antheridium initial into primary 

 spermatogenous cell and tube nucleus; this is the usual shedding stage of this 

 species, with prothallials undivided. 



Fig. 32. — Metaphase of division of antheridium initial showing the twelve 

 gametophytic chromosomes; see a\so fig. 2j. 



Fig. T,i. — Details of nucleus of primary spermatogenous cell of P. totarra 

 Hallii. 



