1914] SHARP— SPERMATOGENESIS IN MA RSI LI A 425 



As the blepharoplast grows in length it gradually becomes more 

 uniform in thickness without passing through such a regular beaded 

 stage as is seen in Equisetum. Our preparations did not permit a 

 more detailed study of this growth, nor was the time of the first 

 appearance of the cilia determined. The blepharoplast often 

 shows a double structure (fig. 37), traces of which are visible in 

 the mature sperm (fig. 42, at middle). Shaw (7) believed this to 

 be an appearance due to the U-shaped cross-section, an idea which 

 is not supported by the present study. 



A more advanced stage in the spiral growth of the nucleus and 

 the blepharoplast is shown in side view and in cross-section in 

 figs. 38 and 39. The blepharoplast grows out freely beyond one 

 end of the crescentic nucleus, a feature again clearly brought out in 

 fig. 40, which represents a cell in which the metamorphosis is about 

 half completed. Cilia are easily made out at this stage. As the 

 transformation continues the nucleus and blepharoplast become 

 more closely compacted and are soon very difficult to distinguish. 



When the sperm escapes from the spore the coils, about 8 in 

 number, are rather closely wound (fig. 41). The first three or four 

 anterior coils are made up of blepharoplast only and bear no cilia. 

 The remaining coils are composed of both blepharoplast and nucleus 

 and bear cilia upon all but the most posterior regions. The large 

 vesicle, held in the posterior coils, contains the cytoplasm of the 

 spermatid with its inclusions, such as an occasional starch grain and 

 other disorganized material of undetermined nature (figs. 37-41). 

 As the sperm swims about, it enlarges through the absorption of 

 water, and when it reaches a denser medium, such as the gelatinous 

 material about the megaspore, the coils become more widely sepa- 

 rated from each other. Such a sperm, fixed over osmic fumes, is 

 shown in fig. 42. It has a length of 50 n, while the newly escaped 

 sperm shown in fig. 41 measures but 15.3 //• 





Discussion 



morphological nature of 



in 



which the reader is referred. Two extracts will suffice to make 

 clear the conclusions reached. 



