20 OSSEOUS TISSUE. 



It has been found that in man as well as in the other mammalia 

 and in birds, the bones in youth, especially in the human race, 

 contain less earthy constituents than those of adults, but that in 

 advanced age, the bones are universally richer in earthy or mineral 

 matters (Thilenius, Davy, Schreyer, Frerichs,* von Bibra). We 

 cannot decide from the facts in our possession whether the dimi- 

 nution of the earthy matters, which has been often observed in 

 the bones of aged persons, is dependent on physiological or patho- 

 logical causes. Different observers have arrived at very different 

 conclusions regarding the ratio of the carbonate to the phosphate 

 of lime at various periods of life. It has been already stated 

 (vol. I, p. 419) that I found far more carbonate of lime in pro- 

 portion to the phosphate in the bones of a new-born child, than in 

 those of an adult and of an old man, while von Bibra found on an 

 average far less carbonate of lime in the bones of young animals. 

 Moreover, von Bibra found rather more phosphate of magnesia in 

 the bones of several very young animals than in the corresponding 

 bones of those that were older. The period of life exerts, accord- 

 ing to Bibra, no essential influence on the amount of fat in the 

 bones. 



It can hardly be doubted that the food must exercise some 

 influence on the constitution of the bones a view which seems 

 proved, not merely by the experiments of Chossat and von Bibra, f 

 (referred to in vol. I, p. 413), but also more especially by the in- 

 vestigations of the latter observer on the bones of different classes 

 of animals. 



It appears from the numerous investigations of von Bibra and 

 Stark on the effects of different kinds of food on the bones of the 

 mammalia^ that the amount of cartilage remained unaffected, but 

 that essential differences were induced in the composition of the 

 inorganic constituents. The bones of the herbivora contain on an 

 average rather more carbonate of lime than those of the carnivora; 

 the bones of the pachydermata and cetacea were found to be 

 especially rich in this salt by von Bibra (who always used the 

 femur in these comparative analyses). There seems to be no per- 

 ceptible difference in the amount of fat in the bones of the carni- 

 vora and herbivora; von Bibra, however, found that the bones 

 of horses contained very much more fat than those of other 

 animals. The bones of fat animals usually contain more oily 



Ann. d. Ch. u, Pharm, Bd, 43, S. 251. 

 t Op. cit. p. 47. 



