248 



ELEMENTS OF HISTOLOGY. [Chap. xxxi. 



dog, are found occasionally, but not very commonly, 

 large mult 1 ' nuclear cells, the nuclei of which are also 

 in one or the other stage of karyokinesis. 



(b) The innermost cells, i.e., the spermatoblasts, 

 become pear-shaped, the nucleus being situated at the 



Fig. 138. From a Section through the Testis of Dog, showing 

 portions of three Seminal Tubules. 



A, Seminal epithelial cells and numerous small cells loosely arranged; B, the 

 small cells or Bpermatobl&sta converted into spermatozoa; c, groups of 

 these in a further stage of development. (Atlas.) 



thinner extremity, becoming at the same time flattened 

 and homogeneous (Fig. 138). The elongation of the 

 spermatoblasts gradually proceeds, and in consequence 

 of this we find numerous elongated, club-shaped sper- 

 matoblasts, each with a flattened nucleus at the thin 

 end. These are the young spermatozoa, the nucleated 

 extremity being the head. 



(c) At the same time these young spermatozoa 

 become grouped together by an interstitial granular 

 substance, in peculiar fan-shaped groups; in these 



