(e) Cells Showing Nucleus and Accessory Nucle- 

 us (Nebenkern). 



Small pieces of a guinea pig's testis were hardened in the 

 following mixture : 



Osmic acid, 2% solution 2 parts. 



Platinum chloride, 2% solution 3 " 



Mercuric chloride, saturated aqueous sol. 5 " 



They are hardened for 24 hours.* embedded in paraffin, sectioned 

 and fixed to cover glasses, stained in iron-lack-hsematoxylin 

 (Haidenhain's), dehydrated, cleared in oil of bergamot, and passed 

 into xylol. Come to the table with a small drop of balsam on your 

 slide. 



Search for tubules showing the last stages of the devel- 

 opment of the spermatozoa. In the cells forming the walls 

 of the seminiferous tubules, the accessory nucleus is stained 

 deeply black, the nucleus a bluish-gray color. Sketch 

 several of the cells showing this structure. 



DRAWINGS FOR LESSON I. 







^/ 



5 



, i 



