THE BONES. 43 



of the ulna are readily felt, both the upper and the lower, and 

 afforded a very ready standard of measurement, called the cubit, 

 from the old Latin name of the bone, cubitus. 



The hand consists of twenty-seven bones, and is divided into 

 three parts, analogous to those of the foot. The solid part enter- 

 ing into the wrist joint is properly called the wrist ; then five long 

 bones make the palm, and fourteen movable pieces superadded, 

 complete the fingers and thumb. It differs from the foot, in its 

 being intended not for support, but for prehension, and all its parts 

 are adapted to this end. Eight small bones are pretty firmly united 

 to form the wrist, presenting a ball superiorly to enter the cavity in 

 the lower end of the radius ; fitted inferiorly to support the bones 

 of the palm ; arched behind to give it strength, and concave in 

 front to permit the blood-vessels, nerves, and sinews, to run to the 

 fingers, without being subjected to undue pressure. In the palm 

 we see the great difference between the hand and the foot. In the 

 latter all the bones of the instep are in one line, immovable, and 

 serving only to rest on. In the former, four of the bones of the 

 palm are placed side by side, to form the hollow of the hand, and 

 support the fingers ; while another, supporting the thumb, is very 

 movable, being capable of being brought opposite the others, so as 

 to grasp firmly anything between them and it. The pieces of the 

 fingers are considerably larger than those of the toes, but are 

 formed on a similar model. The fingers have each three pieces, 

 the thumb only two. The last piece of each is expanded at the 

 end, to support the nail on the back, and on the front the delicate 

 pulp where the nerves ramify, in which the nicest sense of touch 

 exists. 



The size of the skeleton varies very much, varying from thirty- 

 five inches to upwards of eight feet. The gigantic skeleton pre- 

 served in the Museum of the College of Surgeons in London 

 measures eight feet two inches. What is called the middle size in 

 man, is about five feet four, in woman about five feet. 



The formation and growth of bones is an exceedingly interesting 

 subject, but one that can well be studied in the museum, where 

 there are preserved abundant specimens of young children at every 

 different period of foetal life. In the fcetus cartilage serves as a 

 substitute for bone at first : and about the sixth week after concep- 

 tion, earthy matter begins to be deposited in it. In the flat bones, 

 it is first deposited in the centre, and extends in lines radiating to 

 the circumference, forming a delicate net- work like a bit of lace, 



