426 BOTANICAL GAZETTE [November 



Although limited to a single mitosis in the antheridium, the blepharoplast 

 [of Equisetum] retains in its activities the most unmistakable evidences of a 

 centrosome nature, and at the same time shows a metamorphosis strikingly like 

 that in the cycads. In thus combining the main characteristics of true centro- 

 somes with the peculiar features of the most advanced blepharoplasts, it reveals 

 in its ontogeny an outline of the phylogeny of the blepharoplast as it is seen 

 developing through bryophytes, pteridophytes, and gymnosperms, from a 

 functional centrosome to a highly differentiated cilia-bearing organ with very 

 few centrosome resemblances [p. 107]. 



The activities of the blepharoplast in Equisetum, taken together with the 

 behavior of recognized true centrosomes in plants and analogous phenomena 

 in animals, are believed to constitute conclusive evidence in favor of the theory 

 that the blepharoplasts of bryophytes, pteridophytes, and gymnosperms are 

 derived ontogenetically or phylogenetically from centrosomes [p. 113]. 



Marsilia . W 



centrosome 



spermatogenous mitosis, and later divides only 



degenerate without performing any furthei 

 trosome then appears in the same manner 



A new cen- 



the blepharoplast. 



litosis, divides, and occupies 

 mitosis, and in the spermatid 



main with Shaw's (7) 



description, but that writer failed entirely to see the extensive achro- 

 matic structures and the intimate relation they bear to the body 

 in question. Had he done so, it is difficult to understand how he 



the blepharoplast. 



homology of the centrosome 



in 



favor of the centrosome nature of the blepharoplast. We have 

 as yet found no other case in plants where they are emphasized 

 in so striking a fashion. The body divides at each 

 forms the center of an achromatic svstem unmistakablv the same 



mitosis 



centrosomes in alea and animal 



more than mere resemblance 



homology 



fact and is 



sim 



iponding 



centrosomes and has extended itself to three cell generations. 



