SPERMATOGENESIS IN MARSILIA 



LABORATORY 



Lester W. Sharp 



(WITH PLATES XXXIII AND XXXIV) 



Introduction 



In 191 2 the writer (6) published the results of an investigation 

 of spermatogenesis in Equisetum. The principal conclusion was 

 that the blepharoplasts of bryophytes, pteridophytes, and gymno- 

 sperms are derived ontogenetically or phylogenetically from centro- 



somes 



in 



centrosomes and cilia-bearing organs in plants and cer- 



animals, special emphasis being laid upon the 



centrosome-like activity 



Marsilia 



Shaw (7) and by Belajeff (3) in 1898 and 1899, was also used as 

 a strong argument for the centrosome nature of the blepharoplast. 

 Since these accounts show incompleteness and uncertainty with 

 regard to several points, and since the two writers reached contrary 

 theoretical conclusions, it was deemed advisable to examine cer- 

 tain material 1 at hand with a view toward establishing the true state 

 of affairs in Marsilia. 



An extensive historical resume of researches on centrosomes and 

 cilia-bearing structures in plants was presented in the writer's paper 

 on Equisetum and will not be repeated here. To the list of papers 

 given should be added those of Allen (i) and Walker (8) on 

 Polytrichum. In the present work only those dealing with Marsilia 

 need to be reviewed. 



The early papers of Campbell (4, 5) on M . aegyptiaca and M. 

 vestita show the general topography of the male gametophyte. 

 The sequence of wall-formation was not determined in the former 

 species, and great irregularity was reported in the latter. Camp- 

 bell made out none of the cytological details of spermatogenesis. 



1 The writer is indebted to Dr. C. J. Chamberlain* for a portion of the material 



used. 

 419] 



[Botanical Gazette, vol. 58 



