18 



their passage from the glands to their mouths; *lncli 

 is a good contrivance, to prevent their mouths being 

 oppressed by the mucilage, and also to hinder the 

 too plentiful effusion thereof, but yet to afford a due 

 expressure of it at all times, and on all occasions ; 

 particularly in violent and long-continued motions of 

 the join fs, when there is a greater than ordinary ex- 

 pence of it. 



That the nourishment taken in, is continually con- 

 v eyed through the bones, as well as the flesh, appears 

 from an easy experiment^ Mix red liquor with the 

 food of any animals, and in a short time, their bones 

 are died red. When madder root was mixed with the 

 food of a cock, who died after sixteen days, all his 

 bones were red, the internal parts as well as the exter- 

 nal. And the most solid parts were the most 

 deeply tinctured : in swiue the teeth above all the 

 rest. 



5. Annexed to the bones are the cartilages, white, 

 flexible, and smooth \ most of which in process of 

 time become bones, hard and quite void of sense. 



A cartilage is an elastic substance, uniformly com. 

 pact and somewhat transparent, harder and more 

 brittle than a ligament, softer than a bone. It is 

 covered with a fine membrane, folded over the bone, 

 from where the ligament is inserted. Every joint, is 

 inserted with a membrane, which forms a complete 

 bag, and covers every thing within the articulation. 

 The blood-vessels are so small, that they do not admit 

 the red glebules, and are demonstrable only in very 

 young subjects. All round the neck of the bone 

 there are numerous arteries and veins which spread 

 info smaller branches, and communicate with each 

 other. These divide into still smaller branches on 

 the adjoining surface, as they run toward the centre 

 of the cartilage. We can seldom trace them into its 

 substance, because they end abruptly, at the edge of 

 the cartilage. The larger vessels, plunge in by num- 

 berless small holes, and disperse themselves into bran- 



