THE HUMAN SKELETON. 75 



the skull of a female, seventy years of age, weigh but four- 

 teen ounces, while that of a girl, twenty years of age, 

 weighed twenty-four ounces. In the early periods of life, 

 the whole form of the head is much rounder than at an 

 advanced age ; owing, perhaps, to the small development of 

 the face, which the skull envelopes in every direction. 



24. The size of the cavity formed by the bones of the 

 skull, is always proportional to the size of the organs it 

 lodges and protects. The shape and size of the cranium de- 

 pend on the brain, and not of the brain on the cranium. The 

 soft parts model and adapt to themselves the hard, and not 

 the hard, the soft> *The brain is formed before the case 

 which contains it, and it is not till after several years that 

 the bones of the cranium become perfectly consolidated. In 

 a child of ten years of age, afflicted with dropsy in the head 

 from infancy, and which was exhibited a year or two since 

 in this city as a great curiosity, although the head measured 

 thirty-two inches in circumference above the ears, yet nearly 

 the whole surface was protected by a bony covering. 



25 The Spine. However admirably the skull may 

 appear to be adapted to the objects for which it was obviously 

 designed, the spine exhibits no less evidence of wisdom and 

 skill in the divine Architect. In addition to the firmness 

 which was required in the joinings of the bones of the cra- 

 nium, a new principle is now introduced, viz. the attainment 

 of mobility or pliancy. -The spinal column indeed serves 

 three important purposes ; it is the great bond of union be- 

 tween all the parts of the skeleton ; it forms a tube for the 

 safe lodgment of the spinal marrow ; and lastly, it is a pillar 

 to sustain the hear& 



26. In order (o accomplish these various purposes, the 

 back bone, so called, is composed of/twenty-four distinct 

 bones, or \vertebra, from vertere, to turn, ns the body turns on 

 them, which are /arranged into three classes, the cervical, 

 dorsal, and lumbar, The first seven are the cervical, because 

 they belong to the neck ; the next twelve are the dorsal, be- 





