The spermatogenesis of Peripatas (Peripatopsis) balfouri. 285 



the seminal vesicle), the fibre-cells become ruptured in the axis of 

 the testis; but probably in very young testes, before any axial lumen 

 has formed, the branches of those cells form a complete network 

 throughout the testis. Wherever a tuft of spermatocytes is found 

 projecting into the lumen of the testis, a fibre cell forms the sup- 

 porting axis of such a tuft. 



These cells were found particularly large at the proximal portion 

 (Fig. 246) of the abnormal seminal vesicle (described below); and in 

 some of the larger or these cells there were, each enclosed in a 

 separate cytoplasmic vacuole, large deeply-staining globules (Fig. 2i6x). 

 It could not be determined whether these were normal secretions 

 (which I very much doubt), or degeneration products (which would 

 seem more probable), or foreign bodies (as e. g. yolk globules) which 

 had become enclosed in these cells. 



c) The Distal End of the Testis. 

 The distal end of the testis, where it connects with the seminal 

 vesicle, is constricted (Fig. 251, Plate 24). In this region the muscu- 

 lar sheath is greatly thickened, and the separate muscle fibres {M. C) 

 are much thicker. Further, the spermatogonia do not extend into 

 this region, but in their place is found a layer of high, slender gland 

 cells {Gl. C), which nearly fill out the axial cavity. In these gland 

 cells is produced a thin, fluid, structureless secretion , which stains 

 faintly with the Ehrlich-Biondi- Heidenhain stain. 



3. The Seminal Yesicle. 



This is a dilated rounded sack, in the large lumen of which lie, 

 tangled together, spermatozoa and spermatids in various stages of 

 metamorphosis, and in much smaller number, stages from the late 

 prophases of the first maturation division up to the spermatid; this 

 is the best region to study these prophases, especially with regard 

 to the change of form undergone in them, since they lie loosely in 

 the fluid of the lumen and are not compressed together as they are 

 in the testis. All these cells had formed within the testis, and then 

 been discharged into the seminal vesicle ; and on account of the com- 

 parative rarity of spermatids in the testis, it would seem that germ 

 cells of the testis are propelled into the seminal vesicle at about the 

 stage of the second maturation division. Apparently the complete 

 metamorphosis of the spermatozoa, at least of most of them, is ac- 

 complished within the vesicle. 



