230 VITAMIN D GROUP 



comparable increase in calcification. According to Friedman,^" the increase 

 in acidity dnring the healing of rickets is caused by a change in bacterial 

 flora of the intestinal tract, from non-acid-forming bacteria to acid formers. 



8. Bone Ash 



In his early work on rickets in pups Mellanby^'^ observed a decrease in 

 the calcium content of the skeleton of his animals. Telfer^^ found a very low 

 bone ash in his ricketic pups. The percentage of ash in the dry limb bones 

 decreased from 44.9 in the normal controls to 17.7 in the deficient animals. 

 Steenbock and associates^" made comparable observations. Table X gives 

 the percentages of ash in the dry, fat-free femurs of their ricketic and control 

 pups. The decrease in ash content as reported by Steenbock was somewhat 

 less than that given by Teller. 



McCollum and associates^- found a low ash in the bone of ricketic rats. 

 Bethke et al.^^ as well as Dutcher et al.^'^ have made detailed studies of the 

 changes of the bone ash of ricketic rats and correlated the percentages of 

 bone ash with the level of sermn phosphorus. Dutcher and coworkers report 

 a bone ash of 62 % in the dry, fat-free bones from normal rats; in rickets it 

 fell as low as 24 % with an average percentage of 26.5. 



A reduction in the percentage of ash in long bones or ricketic pigs has 

 been reported by Elliot et al}^ and Loeffel et al}^ In a like manner, there is 

 less ash in the bones of ricketic calves than in the norma} controls,^ ,3,56 

 and the same is true for ricketic fowls.-^ The official method for determining 

 vitamin D in poultry feed^^ is based on the increase in the ash of bones of 

 chicks when vitamin D is supplied to animals previously made ricketic. 

 According to Chick et al.,^^ the best criterion of defective calcification is 

 given by the value of the ratio of the amount of ash to the amount of 

 organic material contained in the fat-extracted bone. This is essentially the 

 same as the percentage of ash in the dry, fat-free bone which has been used 

 more frequently. 



BOH. Friedman, /. Nutrition 12, 165 (1936). 



61 S. V. Telfer, Quart. J. Med. 16, 63 (1922-1923). 



B2 E. V. McCollum, N. Simmonds, E. M. Kinney, and C. J. Grieves, Bull. Johns 



Hopk'ins Hosp. 33, 202 (1922). 

 63 R. M. Bethke, H. Steenbock, and M. T. Nelson, J. Biol. Chem. 58, 71 (1923-1924). 

 " R. A. Dutcher, M. Creighton, and H. A. Rothrock, /. Biol. Chem. 66, 401 (1925). 

 85 W. E. Elliot, A. Crichton, and J. B. Orr, Brit. J. Exptl. Pathol. 3, 10 (1922). 

 66 C. F. Huffman and C. W. Duncan, /. Dairy Sci. 18, 511 (1935). 

 6^ Official Methods of Analysis, 7th ed., p. 792. Association of Official Agricultural 



Chemists, 1950. 

 68 H. Chick, V. Korenchevsky, and M. H. Roscoe, Biochem. J. 20, 622 (1926). 



