420 BOTANICAL GAZETTE [November 



In 1898 Belajeff (2) described the development of the male 

 pro thallium in several Hydropteridineae. In Marsilia elata he 

 worked out carefully the exact sequence of walls, which, it will be 

 seen, resembles rather closely that in M. quadrifolia as described 

 below. In the latter species Belajeff did not figure a develop- 

 mental series. 



Shaw (7) in the same year gave an account of the blepharoplast 

 in M. vestita. According to this investigator, a small granule or 

 " blepharoplastoid " appears near each daughter nucleus at the 

 telophase of the second spermatogenous mitosis* During the pro- 

 phases of the third mitosis it divides and then degenerates in the 

 cytoplasm, while a blepharoplast appears near each spindle pole at 

 metaphase. In the following cell generation (spermatid mother 

 cell) the blepharoplast divides to two which occupy positions near ' 

 the spindle poles through the fourth or final mitosis. Each sperma- 

 tid thus receives a blepharoplast. The latter soon shows a small 

 internal granule which multiplies and forms a band; this elongates 

 in close union with the nucleus and bears the cilia. In these facts 

 Shaw found no grounds for the homology of the blepharoplast and 

 the centrosome. 



In the following year Belajeff (3) reported the results of his 

 researches on M. macra and M . vestita. He found centrosomes, 

 which he did not hesitate to call them, at the spindle poles in the 

 last three spermatogenous divisions. With regard to the first 

 division he was uncertain; the figure which he gave as possibly 

 representing the first mitosis almost certainly represents the second. 

 He was inclined to identify the centrosome of the second mitosis 

 with the " blepharoplastoid " of Shaw, but believed it to be con- 

 tinuous from the time of its origin, dividing after each mitosis in 

 preparation for the next, and in the spermatid performing the 

 function of a blepharoplast. Belajeff regarded this as a strong 

 confirmation of his previously stated theory that the blepharoplast 

 and the centrosome are homologous structures. 



In the present paper an attempt will be made to clear up the 

 points left in doubt by these earlier workers, and to add new details 

 which will make it. possible to decide between their divergent 

 views concerning the morphological nature of the blepharoplast. 



