igoS] Y AM ANOUCHI— SPERMATOGENESIS AND OOGENESIS 147 



to the final mitosis in the antheridium which differentiates the sper- 

 matids. At this final division each spermatid receives a blepharo- 

 plast which lies close beside the nucleus. The blepharoplast begins 

 to elongate and its elongation is followed by that of the nucleus, so 

 that both structures form two parallel bands which take a spiral 

 form. 



Shaw's paper (80) on Onoclea and Marsilia appeared almost 

 simultaneously with the foregoing contribution of Belajeff. He 

 investigated the cell divisions preceding the formation of the spermatid 

 in Marsilia and found two small bodies, which he called " blepharo- 

 plastoids," first in the daughter nuclei after the mitosis which 

 differentiates the spermatid grandmother cell. There is one 

 blepharoplastoid, therefore, for each nucleus of the grandmother cell 

 of the spermatid. This blepharoplastoid divides, but the halves re- 

 main close together and pass to one side of the cell. With the next 

 mitosis which occurs in the grandmother cell two new blepharoplasts 

 appear at the pole of the spindle, and they accompany each daughter 

 nucleus after this mitosis into the spermatid mother cell. Then each 

 divides, and after the division of the spermatid mother cell, a 

 blepharoplast is included in each spermatid. 



The next year Belajeff (7) studied Gymnogramme and also the 

 same species of Marsilia which Shaw had investigated. He found 

 centrosome-like bodies at the poles of spindles in various mitoses pre- 

 ceding the formation of the spermatids with their unquestioned 

 blepharoplasts, and he also found the blepharoplasts at the poles of 

 the spindle. From this he drew the conclusion that the blepharoplast 

 of Marsilia holds the same relation to the pole of the spindle as does a 

 centrosome. 



Thom (88) in the same year observed a blepharoplast in the sperma- 

 tids of Adiantum and Aspidium as a round body beside the nucleus. 

 He states that the disappearance of nucleoli at the time of the appear- 

 ance of the blepharoplast would suggest a relationship between them. 

 According to his observation the modification of the blepharoplast 

 into a band structure is considerably delayed after the transformation 

 of the nucleus. 



No contribution based upon the original investigation of sperma- 

 togenesis in pteridophytes has been published since Thom's paper 



