848 



DEVELOPMENT OF SPERMATOZOA. 



tail and the middle piece (III, t). Between the spermatoblasts are numerous round 

 amceboid cells devoid of an envelope, and connected to each other by processes. 



Fig. 636. 

 Spermatozoa. 1, human ( x 600), the head seen from the side ; 2, on edge ; k, head ; m, middle 

 piece ; /, tail ; c, terminal filament ; 3, from the mouse ; 4, bothriocephalus latus ; 5, 

 deer ; 6, mole ; 7, green woodpecker ; 8, black swan ; 9, from a cross between a goldfinch 

 (M) and a canary (F) ; 10, from cobitis. 



They seem to secrete the fluid part of the semen, and they may therefore be called 

 seminal cells (I, , II, III, IV, p). A spermatozoon, therefore, is a detached 



Fig. 637. 

 Semi-diagrammatic spermatogenesis : I, transverse section of a seminal tubule a, membrane ; 

 b, protoplasmic inner lining ; c, spermatoblast ; s, seminal cells. II, Unripe spermatoblast 

 /, rounded clavate lobules ; p, seminal cells. IV, spermatoblast, with ripe spermatozoa 

 (fr) not yet detached ; tail, r ; n, wall of the seminal tubule ; h, its protoplasmic layer. III. 

 spermatoblast with a spermatozoon free, t. 



independently mobile cilium of an enlarged epithelial cell. Some observers adhere 



