110 ELEMENTARY PHYSIOLOGY. [x. 



of a frog as in Less. v. B. § 2 and mount in 

 glycerine a sector of it, including its junction 

 with the sclerotic. Note 



a. The small separate bundles of nerve fibres 

 entering the cornea at its periphery; the 

 meduUated fibres on account of their me- 

 dulla are more deeply stained than the non- 

 medullated. 



b. Trace as far as possible the course of one of 

 the nerve bundles; the medulla soon dis- 

 appears, the fibres, still showing nuclei at 

 intervals, join with the fibres from other 

 bundles to form a coarse plexus; from this 

 proceeds a plexus of smaller bands which 

 have few nuclei ; finally from this plexus run 

 very fine varicose non-nucleated nerve-fibrils 

 in straight Unes across the cornea (these fine 

 fibrils may also be seen forming part of the 

 finer bands of the plexus). 



D. Spinal Ganglia. 



1. Take a mammal's spinal ganglion (e.g. a dorsal 

 spinal ganglion of a cat or dog) which has been 

 preserved in ammonium bichromate 2 p. c. about 

 three weeks, and subsequently in spirit. Prepare 

 sections passing through the trunk of the nerve, 

 the ganglion, and the anterior and posterior 

 roots of the nerve. Stain with hsematoxylin or 

 carmine, clear (cp. p. 75) and mount in Canada 

 balsam. 



