i9 1 2] SHARP— SPERMATOGENESIS IX EQUISETUM 91 



sides of the cell, occupy the spindle poles, and disappear at the close 

 of mitosis. It is possible that they are included within the mem- 

 branes of the daughter nuclei. After the last (diagonal) division, 

 however, they remain in the cytoplasm as the blepharoplasts, 

 elongating and bearing two cilia. Ikeno regards these bodies as 

 true centrosomes. He further believes that the blepharoplasts of 

 pteridophytes and gymnosperms are derived ontogenetically or 

 phylogenetically from centrosomes, but that all bodies called centro- 

 somes in plants may not be homologous. In a paper appearing 

 two years later, Miyake (66) states that although an inconstant 

 aster, often with a dot at the focus, may appear in the spermatoge- 

 nous divisions, no body like Ikeno 9 s centrosome is present, except 

 at the last mitosis, when a bodv lies at each soindle Dole as figured 



by that author. 



the same resuJ 

 Makinoa. Miy 



centrosome hitherto reported in the cells of the Hepaticae is nothing 

 but a center of cytoplasmic radiation, and inclines toward the view 



homologous structures. 



centrosome 



Mar chant 



.permatid 



cell in contact with the plasma membrane. These occupy the 

 spindle poles and in the spermatids function as blepharoplasts. 

 Escoyez regards these organs as distinct from centrosomes, though 

 their origin was not traced. Centrosomes are reported by Schaff - 

 ner (74) in all the spermatogenous divisions in Marchantia. After 

 the last mitosis these behave as blepharoplasts, which are conse- 

 quently looked upon as modified centrosomes. Bolleter (8) 

 found in Fegatella a centrosome-like body near the spindle pole at 

 the last division and observed its nuclear origin. He believes that 

 it is present in the earlier division also. 



In the antheridium of Riccia Lewis (6i) reports centrosome-like 

 structures in the early and diagonal divisions. These apparently 



asm 



mitosis 



when they persist and become the blepharoplasts. Lewis does 

 not think these bodies represent centrosomes. 



The most recent investigations of the blepharoplast in bryo- 



