^6o BOTANICAL GAZETTE 



[iL\RCH 



(fig 



described 



o 



mitosis 



best stage for an accurate counting 



■ge number 



anaphase, m which trv-o sets of daughter chromosomes are regularly 

 arranged near the poles {fig. 57). The polar view of this stage showed 

 128 or 132, or in rare cases 130, chromosomes {fig. 58). 



Mitoses that occur following this first segmentation division, during 

 the development of the embr}-o, were traced up to the appearance of 

 the fii^t leaf. The process is essentially similar, and 128 or 132 

 chromosomes are invariahk- nrpc^^tit 



Discussion of cytological phenomena 



The origin of the blepharopIasL— There have been many contribu- 

 tions concerning the origin and structure of the blepharoplast, not only 



m sperms of gymnosperms and pferidophytes, but also in zoospores of 

 thalloph}tes. 



In Cycas (Ikeno 41, 42, 43, 48), Ginkgo (Hir.\se 36, 37, 48), 

 and Zamia (Webber 94, 95, 96), two blepharoplasts first are formed 

 de novo in the cytoplasm of the body cell at some distance from the 

 nucleus, and one of these blepharoplasts is included in each sperma- 

 tid; accordingly the origin of the blepharoplast is cytoplasmic. 



In Equisetum and Gymnogramme, Belajefe (6) observed the 

 blepharoplasts as two deeply stained bodies on opposite sides of the 

 nucleus previous to the final mitosis which differentiates the spermatid. 



In Marsilia Sh.\w (80) 



in the 



mitosis which differentiates the grandmother 



spermatid. The blepharoplastoids disappear in the spermatid grand- 

 mother ceU, in which two new blepharoplasts are formed at the poles of 

 the spmdle. BELAjErr (7) examined the same form which Shaw had 

 studied, and he found two centrosome-like bodies at the poles of the 

 spmdle of the mitosis which gives rise to the spermatid grandmother 

 ceH. These centrosome-like bodies are probably structures simflar to 

 the blepharoplastoids of Sh.\w; however, according to BEiAjErr's 

 accounts, these structures do not pass into the cytoplasm to disappear, 

 but accompany each daughter nucleus in the telophase and in the 

 prophase of the next mitosis which occurs in the spermatid grand- 

 mother cell. This centrosome-like body divides and the two resulting 



