18 THE FRAMEWORK OF THE HODY 



the body. Some bones are long and cylindrical, like the 

 humerus; some are short and thick, lik^ the bones of the 

 wrist; some are flat and thin, like the bones of the skull; 

 some are irregular in shape, like the vertebrae. The longest 

 bone of the human body is the femur, wh^ch may be as much 

 as eighteen inches in length ; from this the size of different 

 bones varies greatly all the way to the tiny bones in the middle 

 ear. Bones are composed of both mineral and animal matter, 

 united in the proportion of two parts of the former to one of 

 the latter. The mineral matter is chiefly phosphate of lime; 

 the animal matter is gelatin. We may separate each of these 

 substances from the other for examination. First, if we burn 

 a bone for several hours on a good bed of coals, the gelatin is 

 entirely removed. There remains a beautiful white specimen 

 of phosphate of liine, which preserves the shape of the bone 

 perfectly, but is brittle and incapable of sustaining any con- 

 siderable weight. To remove the mineral matter we use acid. 

 A sheep's rib, thoroughly cleaned, or bones from a roast fowl, 

 should be allowed to stand in dilute muriatic acid (one part 

 acid to eight parts water) for two or three days, when the 

 phosphate of lime will be dissolved and only the gelatin 

 remain, but as before, the shape of tre bone is preserved, 

 the bone being now, however, soft and pliable. The specimen 

 may be preserved in alcohol. 



4. If, for any reason, either of these ingredients is dispro- 

 portionate in the bone during life, the body is in danger. The 

 mineral substance is useful in giving rigidity of form, while 

 the animal substance insures toughness and elasticity, so that 



1. Some Properties of Bone. " The power of bone to resist decay is 

 remarkable. Fossil bones deposited in the ground long before the appear- 

 ance of man upon the earth have been found by Cuvier, exhibiting a 

 considerable portion of cartilage. The jaw of the Cambridge Mastodon 

 contained over forty per cent of animal matter enough to make a good 

 glue and others about the same. From this we see that a nutritious 

 soup might be made from the bones of animals that lived before the 

 creation of man. The teeth resemble bone in their structure, but resist 

 decay longer ; they are brought up by deep-sea dredging, when all other 

 parts of the animal have wasted away. The bones differ at different ages, 



3. Shape of bones ? Size ? Composition ? 4. Animal and mineral substance ? 



