160 CONDITIONS OF HEALTH IN BONES. 



The beneficial effects of exercise and diet in im- 

 parting solidity to the bones have not escaped the 

 observation of trainers. Sir John Sinclair ex- 

 pressly mentions that the bones become, in a re- 

 markable degree, harder and tougher, and less liable 

 to be injured by blows or accidents. Testimony of 

 this kind ought to be of great weight, as based, not 

 on theory, but on the broad and well-marked ex- 

 perience of practical men.* 



It must be observed, however, that defective nu- 

 trition may arise from other causes than inadequate 

 exercise ; but even then, the consequences attending 

 it are analogous in their nature. Among the pooi 

 it often arises from deficiency of wholesome food, 

 and from damp dark habitations ; among the rich, 

 from feeble digestive and assimilating powers, and 

 pampering in diet ; and also from errors in clothing, 

 and neglect of sufficient ventilation, and due expo- 

 sure to the open air. Rickets, softness of the bones, 

 and white swelling are accordingly observed to be 

 almost confined to children belonging to one or other 

 of these classes. 



To understand more clearly the relative uses of 

 bones and muscles, we may be allowed to use a 

 comparison, although, like all other comparisons, it 

 presents many points of difference. The bones are 

 to the body what the mast and spars are to a ship ; 

 they give support and the power of resistance : and 

 the muscles are to the bones what the ropes are to 

 the masts and spars. It is to the muscles that the 

 bones are indebted for the power of preserving or 

 changing their relative position. If the bones or 

 masts are too feeble in proportion to the weight 

 which they are required to sustain, then a deviation 

 from their shape and position takes place ; and on 

 the other hand, if the muscles or ropes are not suffi- 

 ciently strong and well braced, then insufficiency of 



* Code of Health, 5th edit. Appendix, p. 35. 



