^ 



SOUTHERN BRANCr,, 



UNIVERSITY OF CALIFORNIA 



LIBRARY, 



ANGELES, GAL IF. 



Preliminary notes on the embryology of Reboulia hemisphaerica 



WILLIAM L. WOODBURN 

 (WITH PLATE 19) 



The object of this paper is to present a part of a more extended 

 study on the embryology and cytology of Reboulia hemisphaerica 

 (L.) Raddi. Only certain stages in the process of fertilization and 

 in the early development of the embryo sporophyte will be con- 

 sidered at this time. The description of various other stages in 

 the life history together with a summary of the previous literature 

 on Reboulia will be left for a subsequent report. 



FERTILIZATION 



The male gamete in the bryophytes may undergo two series 

 of marked morphological changes. The first series includes the 

 steps leading from the non-motile condition of the androcyte 

 (the cell which directly becomes transformed into the mature 

 sperm) through the formation of the actively motile free-swim- 

 ming sperm. The second series includes the reverse steps and 

 occurs in those cases where a sperm reaches an egg. In this 

 second case the motile sperm becomes again non-motile with a 

 resting nucleus similar to that of the androcyte or androcyte 

 mother-cell. Details of the main stages in the first series have 

 been carefully described for numerous liverworts and mosses. 

 The processes accomplished in the second series, after the sperm 

 reaches the egg, are not so well known. However, soon after 



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