154 



ELEMENTARY BIOLOGY. 



[CHA 



21. 



year, 

 deep 



and may be one or more layers of cells 



II 



The spermatozoa. 



i. Tease up a small piece of the fresh testis in 

 magenta solution. If spermatozoids are present, 

 each will be seen to consist of 



a. Head; rod-like, generally straight, more rarely 

 arched, mainly composed of a deep-staining 

 body {nucleus). 



/?. Tail ; elongated and flagelliform, stains but 

 feebly, if at all. In favourable specimens it 

 may be seen to be continuous with a small 

 amount of clear protoplasm which surrounds 

 the "head." 



ii. Compare the aggregates of spermatozoa seen in 

 the prepared section. The applied heads of 

 many of them will be seen to be capped by a 

 large irregular nucleated cell (last remnant of 

 parent cells of the group). 



iii. Compare the living spermatozoa, if accessible, 

 obtained from either the testis or vas defere 

 Note the nature of their movements. 



1 



I 



The ovary. 



Prepare transverse sections of an ovary : — alcoho, 

 borax-carmine, Canada balsam. 



Examine under a low power. 



a. The ova {ovisacs) ; variable in size : smaller 

 ones, seen to consist of granular protoplasm 

 with a large germinal vesicle (nucleus) : larger 

 ones, pigmented peripherally; germinal vesicle 



