Nos. 451-452.] STUDIES ON THE PLANT CELL. 581 



There has been some discussion on the morphology of these 

 motile sperms of the gymnosperms. The claim has been made 

 that they are ciliated spermatids (sperm mother-cells) and there- 

 fore different from the sperms of pteridophytes which are 

 formed inside of mother-cells that upon their escape are left 

 behind as empty cysts. However a close analysis of their struc- 

 ture will show that the sperms in both groups have an identical 

 protoplasmic organization. There is a nucleus and a greater or 

 less amount of cytoplasm in which the blepharoplast lies and the 

 entire structure is surrounded by a plasma membrane. Any 

 differences in the processes of spermatogenesis can only concern 

 the greater or less development of a cellulose membrane around 

 the spermatids. It may be true that this cellulose membrane 

 is entirely absent in Cycas and Zamia, but if present it would 

 be merely a shell like envelope around the sperm and cannot 

 affect its morphological unity and agreement with the sperms 

 of pteridophytes. A comparative study of the composition and 

 formation of the walls enclosing sperm nuclei in the sperma- 

 tophytes is much needed to carefully distinguish between plasma 

 membranes and the cellulose secretions that may be developed 

 by them. 



While the cycads and Ginko have very much the largest 

 sperms known and are consequently extremely favorable for an 

 examination of spermatogenesis nevertheless some surprisingly 

 detailed studies have been made among the Filicineae and Equise- 

 tinese. Following his preliminary announcements ('97a, '97b, 

 '97c), Belajeff published in '98 an account of spermatogenesis in 

 Gymnogramme and Equisetum. These forms present histories 

 parallel to each other and to the cycads. Two deeply staining 

 bodies (blepharoplasts) appear on opposite sides of each nucleus 

 previous to the final mitosis in the antheridium which differen- 

 tiates the spermatids. Consequently each spermatid receives a 

 blepharoplast which lies close beside the nucleus. The bleph- 

 aroplast begins to elongate and is followed by the nucleus so 

 that both structures form two parallel bands which take a spiral 

 form. (Illustrated in Fig. 3/2 of Section I.) The rest of the 

 cytoplasm remains as a vesicle which comes to lie at the larger 

 end of the sperm. The cilia of Equisetum could be traced to 



