THE HINGES. 



95 



up. It is as if the ends of the two joints were 

 put into the two open ends of a short cylinder, 

 or rather of a short bag or ptirse, and the open 

 ends were then gathered round, and fastened 

 tightly to the two bones. Do you not see 

 that, in this way, the joint would be completely 

 shut up, as in a sack ? 



CAPSULES. These bags or sacks are called 

 capsules. Their use is to keep the joint from 



