ROBERT H. BOWEN. 



other hand, the moss androcytes possess a small blepharoplast 

 which remains morphologically distinct from a filament (the bulk 

 of Allen's blepharoplast) that grows from it posteriorly. My 

 studies clearly support the latter description. At an early stage 

 (Fig. 15) there is a small, definite blepharoplast or central body 

 to which is attached a delicate filament. Subsequently (Fig. 16), 

 the central body becomes somewhat larger and more conspicuous 

 (as is common also in animal spermatids), and the filament 

 grows rapidly back over the nucleus. When the nucleus begins 

 to elongate, its anterior tip is attached to the posterior end of 

 the centriole (Fig. 18), a relation which probably is maintained 

 in the completed sperm. But the extraordinary thing is that 

 the filament, at first apparently single, soon becomes clearly 

 multiple. Benda preparations, which stain the filament very 

 sharply, show at least two filaments which separate sufficiently 

 at chance places to be clearly demonstrated. There are some- 

 times indications of a third filament, though this seems at 

 present to be doubtful. It is my suggestion that these two 

 filaments are the well-known free filaments of the mature sperm. 

 After the sperm is well along in its differentiation they probably 

 break loose from their association with the body of the sperm, 

 and thus Allen's failure to follow them clearly in their growth 

 would be logically accounted for. I believe that the observations 

 here recorded leave no doubt that the body to which the filaments 

 are attached is a true centriole comparable in every way to the 

 central bodies of animal cells. 



This brief outline of sperm formation in mosses clears up 

 many points which long have been a puzzle to cytologists. It 

 leaves the fate and possible homologies of the plastidome in 

 an unsettled condition, but I have hopes that by the time my 

 study is ended this gap will have been closed at least in part. 

 The results here given in outline will be reported in detail in 

 a series of papers of which the first will soon be ready for 

 publication. 



