1908] YAMANOUCHI— SPERMATOGENESIS AND OOGENESIS 155 



the coil takes on a round sausage-shape (fig. 30), which gradually 

 passes into a band structure (fig. 2Q). This band becomes more 

 and more narrow, with a gradual diminution of its width, but this 

 diminution is compensated for by a coalescence with the tapering end 

 of the band-shaped blepharoplast; so that now the tapering end of 

 the blepharoplast runs with the nuclear band as far as the latter struc- 

 ture goes, and finally the blepharoplast ends in the wedge-shaped 

 band. Then the outer surface of that part of the coiled band, 

 which is composed of the blepharoplast and nucleus by their parallel 

 coalescence, becomes covered by the blepharoplast, which grows 

 extensively. 



The structure of the coiled nuclear region becomes more and more 

 compact, during this metamorphosis of the nucleus, by the gradual 

 condensation and aggregation of clumps of the chromatin reticulum. 

 Thus the general structure of the coiled sperm is organized within the 

 spermatid. By this time, numerous cilia are observed growing on 

 the surface of the coiled band of the blepharoplast (fig. ji). During 

 this modification of the nucleus and blepharoplast, the Nebenkern is 

 always present in a definite position close to the nucleus, and when 

 the coiled form of the sperm is established, the Nebenkern is observed 

 near the blunt end of the sausage-shaped portion without entering 

 into the construction of the body of the sperm (fig. 32). 



The mature sperm when observed within the spermatid consists 

 of 2 . 75 coils, 1 . 5 of which are composed of the blepharoplast with the 

 nuclear substance lining a certain distance, and the rest exclusively 

 of the nucleus. When the spermatids are discharged from the anther- 

 idium the anterior part of the sperm, which consists of the blepharo- 

 plast with cilia, first protrudes from the membrane of the spermatid, 

 the membrane being so delicate at this time that it looks like a thin 

 film of cytoplasm. As soon as the sperm begins to swim freely, the 

 cytoplasmic substance with the Nebenkern is attached to the posterior 

 coil of the sperm as a vesicle (fig. jj). The number of coils in the 

 swimming sperm varies, but an average in material quickly killed is 

 observed to be 2.75 coils. Numerous cilia grow from the whole of 

 the surface of the band-shaped blepharoplast, their length some- 

 times surpassing more than twice the length of the body of the 

 sperm. 



