46 



stage this process is further advanced in the male than in 

 the female. During September the tubules are of small 

 diameter, no greater than that of an interspace in the 

 reticulum. The structure of the cells composing the 

 germinal epithelium of this stage is nearly similar in both 

 sexes. An irregular laj^er of cells is supported on a base- 

 ment membrane. The female germinal epithehum (PI. II., 

 fig. 7, ep. ger.) can be distinguished by the large nuclei of 

 the cells. At this stage it consists of few cells, and the 

 first few ova separated off fill the lumen of the tubule. 

 Proliferation is a more rapid process in the male, and in 

 a short time the tubules are filled with cells, resulting 

 from the divisions in the germinal epithelium. Most of 

 these cells become spermatoblasts, and divide subsequently 

 to form the spermatozoa, but many of those separated off 

 at this stage become modified to form the system of sup- 

 porting filaments so conspicuous at later stages (PI. II., 

 fig. 5, sup. fil.) The cell migrates towards the centre of 

 the tubule, becomes slightly elongated in a radial direc- 

 tion, and its outer end becomes frayed out into one or 

 more delicate filaments, which seem to retain some con- 

 nection with the wall of the tubule. The nucleus and 

 cell body then break down and disappear, and a group of 

 filaments is left arranged radially in the lumen of the 

 tubule, on which the spermatozoa formed at this time, 

 and subsequently are arranged in rows. In the smaller 

 and terminal portions of the tubules the whole epithelium 

 takes part in the formation of spermatozoa or ova, accord- 

 ing to the sex, but in the larger branches, and this is the 

 more common appearance in the sections, the tubule 

 possesses a longitudinal strip of columnar epithelium, 

 cells with clear cell bodies, and with long ciha projecting 

 into the lumen. This strip of ciliated epithehum extends 

 round the tubule for about one-fourth or less of the cir- 



