2 ZOOTOMY. 



skeleton may be either kept in spirit or prepared 

 as follows : — 



(a) Place for about three days in a solution 

 composed of 



Glycerine . ro parts. 



Water lo ,, 



Corrosive sublimate . . o'l ,, 

 Alum . . o'2 ,, 



{b) Transfer to melted glycerine jelly made by 

 dissolving 2 parts of gelatine, or " gelatine glue," 

 in the above fluid : allow to remain for 2 to 4 days 

 at a temperature just sufficient to keep the jelly 

 fluid. 



{c) Place in a dry room, until the surface no 

 longer feels damp or sticky ; then varnish with a 

 solution of white (bleached) shellac in rectified 

 spirit. 

 II. In the prepared skeleton make out the following 

 points : — 



1. The notochord (Fig. i, nc), a cylindrical rod, occupy- 

 ing the position of the vertebral column in one of the 

 higher animals ; at its anterior end it tapers to a point some- 

 what suddenly ; at its posterior end the tapering is more 

 gradual. It is composed of a strong sheath of cartilage, 

 inclosing a gelatinous central substance (Figs. 4, 6, 7, 8, nc). 



2. The neural processes (Fig. i and 6 n.p), small rods 

 of cartilage, set in pairs at short intervals alongthe dorso-lateral 

 regions of the notochord, and partly inclosing the neural 

 canal (Figs. 4 and 6 — 8, n.ca), in which the spinal cord 

 lies. Between the neural processes and completing the 

 shutting-in of the neural canal both dorsally and laterally is 

 a quantity of very tough pigmented fibrous tissue (Figs. 4, 

 and 6—8, f.t). 



