1912] SHARP— SPERMATOGENESIS IN EQUISETUM 101 



to one cilium. The further details of cilium development were not 



i 



worked out. 



The blepharoplast granules, which have been lying close together 

 or in contact, now fuse to form a continuous thread. The coales- 

 cence usually begins at one end of the chain so that at certain 

 stages it appears solid at one extremity and broken at the other 

 (fig. 22). The union, although intimate, is not so complete that 

 the thread is uniform in diameter throughout, even in the later 

 stages. When the metamorphosis of the spermatid is half complete 

 the beaded nature of the blepharoplast is clearly evident, and when 

 the spermatozoids are mature it still shows an uneven outline. 



Immediate' y after the union of the granules the nucleus begins 

 to show marked changes. It moves to one side of the cell and 

 begins to draw out into a flattened point next to the blepharoplast 

 (fig- 2 3)- At this stage the nucleus and the blepharoplast lie rather 

 close together; the relative position of the two is seen in fig. 24, 



similar cell viewed from 



tion a. 



assumes 



form, while its reticulum becomes 



staining (fig. 25). The blepharoplast also lengthens spirally, and 

 the two become widely separated from one another. Figs. 26 and 

 27 represent respectively an entire cell like that of fig. 25 viewed 



from 



No connections 



other than the undifferentiated cytoplasm are present between the 

 nucleus and the blepharoplast. The cilia have now increased 

 markedly in length. 



As previously noted, the mature spermatozoids vary greatly in 

 size in different antheridia, which may be seen by comparing 

 tigs. 28 and 29. The nucleus now stains intensely with iron- 

 hematoxylin. Its surface presents a mottled appearance while 

 rery lightly stained sections show that its interior is quite homo- 



\ 



with several verv small 



mos 



the 



origin and nature were not determined. A few vacuoles are present 

 in the cytoplasm. The blepharoplast continues its spiral growth 

 until it has made about 1.4 turns. The nucleus makes 0.7 of a 



