I.] THE FROG. 139 



10. Nerve-cells. 



a. Unipolar cells. w 

 i. Take a spinal ganglion from a recently-killed 



frog and tease up under a low power in eosin 

 solution. Among the pigment cells and other 

 small cells present, the above-named will be 

 seen as large round or oval pale granular cells, 

 each with a conspicuous large round nucleus. 

 Examine under a high power. 

 a. The cell-body; granular, and connected at its 



base with a single nerve-fibre (unipolar-cell). 

 p. The nucleus; generally central in position; 



invariably containing one large nucleolus, 

 y. The cell capsule; a delicate nucleated invest- 

 ment which may or may not be torn away. 



ii. Tease up a second spinal ganglion, and treat 

 with osmic acid and glycerine, as directed at 

 9. iii. Examine under a high power. 



a. General. Cf. supra. 



/3. The polar plate; consisting of two or more 

 clear cells, situated at the base of the unipolar 

 cell and in direct connection with the ulti- 

 mate termination of the nerve fibre. 



b. Bipolar cells. 



Take a sympathetic ganglion from a recently- 

 killed frog and tease it up in eosin as directed 

 above. Examine under a low power. Among 

 the pigment and other cells present, will be 

 seen numerous large pale granular cells some- 

 what like the unipolar ones. Examine under a 

 high power. 



