134 PRACTICAL HISTOLOGY [XVII 



b. Note in the carotid artery that the elastic part 

 of the inner coat is chiefly represented by a refractive, 

 and (probably) wavy lamina ; and that the elastic tissue 

 is comparatively scanty in the middle coat. 



c. Note in the vein that the whole wall is thinner; 

 the inner coat is inconspicuous, except as regards the 

 nuclei of its endothelium ; the middle coat is much 

 thinner than the outer. 



2. Cut open longitudinally the jugular, or other 

 large vein of a freshly killed rabbit. Pin it out with 

 hedgehog quills, stream it with *75 p.c. sodium sulphate 

 for a moment, add *2 p.c. nitrate of silver and leave 

 for 10 minutes, wash in distilled water, expose to light 

 for half-an-hour, pass through alcohols, clove oil, and 

 mount in balsam. 



Observe the rather jagged dark lines of the cement 

 substance between the cells ; the cells form a continuous 

 layer, are more or less elongated in a longitudinal 

 direction, and are flat ; indications of their nuclei may 

 be seen, and in some places indications also of the 

 fibres of the muscular coat as transverse or longitudinal 

 markings caused by a deposition of silver in the cement 

 substance between the muscle cells. If the vein has 

 been left too long in the silver nitrate solution, or 

 exposed too long to light, silver will be deposited in 

 the substance of the cells also. 



3. Tear off a strip from the inner coat of a 

 medium-sized artery (potassium bichromate '2 p.c. for 

 two to six days; it may be kept in dilute glycerine). 



