A STUDY OF THE SKELETON 



183 



like all other protoplasm, require proteid and water; the fats 

 and carbohydrates of food are probably converted into fatty 

 marrow; while the intercellular substance is formed from 

 the mineral matters brought by the blood. Milk is a most 

 important article of diet in 

 early life, since in addition to 

 the other nutrients, it supplies 

 the phosphate of lime needed 

 for bone manufacture. In the 

 process of refining wheat flour 

 much of the mineral matter is 

 lost; for this reason whole 

 wheat flour and the coarser 

 cereals like corn, rye, and oats 

 are much more valuable as 

 bone builders, and are espe- 

 cially needful during the period 

 of growth. The insoluble min- 

 eral matters in these foods are 

 made soluble by the gastric 

 juice in the stomach. The 

 soluble salts are then supplied 

 by the blood to the bone cells, 

 and these in turn convert this 

 mineral matter into the hard 

 intercellular substance. 



Effect of Pressure on Bones. 

 Tight-fitting clothing is a most 

 important factor in modifying 

 permanently the shape and po- 

 sition of bones. Normal growth cannot be attained if 

 the skeleton is subjected to pressure. Yet this important 

 principle of hygiene is constantly violated by women who 

 wear tight-fitting clothing about the waist. Baneful fashion 

 is often followed even in youth, when the skeleton yields 

 readily to pressure. The result is that the ribs are perma- 



FIG. 78. Pivot Joint of Right 

 Arm. 



A = position of bones when back 



of hand is down. 

 B = position of bones when palm 



of hand is down. 

 H= humerus. 

 R = radius. 

 U = ulna. 



