DISEASES OF THE BONES. 555 



We do not possess trustworthy information in regard to the compo- 

 sition of bones at different ages. The analyses by E. VOIT of bones of 

 dogs, and by BRUBACHER of bones of children, apparently indicate that 

 the skeleton becomes poorer in water and richer in ash with increase 

 in age. GRAFFENBERGER 1 has found in rabbits, 6|-7J years old, that 

 the bones contained only 140-170 p. m. water, while the bones of the 

 full-grown rabbit 2-4 years old contained 200-240 p. m. The bones of 

 old rabbits contain more carbon dioxide and less calcium phosphate. 



The composition of bones of animals of different species is but little known. 

 The bones of birds contain, as a rule, somewhat more water than those of mam- 

 malia, and the bones of fishes contain the largest quantity of water. The bones 

 of fishes and amphibians contain a greater amount of organic substance. The 

 bones of pachyderms and cetaceans contain a large proportion of calcium carbo- 

 nate; those of granivorous birds always contain silicic acid. The bone-ash of 

 amphibians and fishes contains sodium sulphate. The bones of fishes seem to 

 contain more soluble salts than the bones of other animals. 



A great many experiments have been made to determine the exchange 

 of material in the bones for instance, with food rich in lime and with 

 food deficient in lime but the results have always been doubtful or 

 contradictory. The attempts to substitute other alkaline earths or 

 alumina for the lime of the bones have also given conflicting results. 2 

 On feeding sufficient calcium and phosphorus in the food ARON 3 found, 

 by strongly reducing the sodium and at the same time giving a large 

 amount of potassium, that the development of the bones was below 

 normal. On the administration of madder, the bones of the animal are 

 found to be colored red after a few days or weeks; but these experiments 

 have not led to any positive conclusion in regard to the growth or 

 metabolism in the bones. 



Under pathological conditions, as in rachitis and softening of the 

 bones, an ossein has been found which does not give any typical gelatin 

 on boiling with water. This finding is still uncertain as otherwise path- 

 ological conditions seem to affect chiefly the quantitative composition 

 of the bones, and especially the relation between the organic and the inor- 

 ganic substance. In rachitis the bones are poorer in solids and these 

 are poorer in mineral substances than under normal conditions. 

 Attempts have been made to produce rachitis in animals by the use of 

 food deficient in lime. From experiments on fully developed animals 

 opposing results have been obtained. In young, undeveloped animals 



1 Voit, Zeitschr. f. Biologie, 16; Brubacher, ibid., 27; Graff enberger in Maly's 

 Jahresber., 21. 



2 See H. Weiske, Zeitschr. f. Biologie, 31, and W. Stoeltzner, Pfluger's Arch., 122, 

 and H. Stoeltzner, Bioch. Zeitechr., 12. 



3 Pfluger's Arch., 106. 



