METABOLISM IN DISEASES OF BONES AND JOINTS 737 



(&), whose experiments are both interesting and conclusive, starved 

 cats for a month or more, analyzed the excreta, and, at the end of the 

 period, analyzed the bones and compared the results with those of normal 

 cats. The amount of calcium excreted which came from the bones was 

 equivalent to one per cent per day of the total bone of the cat. Sedlmair's 

 bone analyses showed in addition that there was a loss of from 4.6 to 13.8 

 per cent of the ash, and from 2.5 to 11.6 per cent of the calcium oxid 

 of the bones. In one cat there was a loss of 13.8 per cent ash, 11.6 per 

 cent calcium oxid, and 12.8 per cent ossein results which are close 

 enough to suggest that the organic and inorganic' materials of the cell 

 are destroyed together. Wellman has found similar, results in the 

 rabbit. 



Studies of the phosphate metabolism lead to the same conclusion as 

 studies of the calcium metabolism. It is commonly stated that the excre- 

 tion of nitrogen and phosphorus are nearly parallel ; that the ratio N :P in 

 the excreta is almost constant, and, on the average, is about, the ratio in 

 which these elements occur in flesh, so that theoretically the phosphorus 

 excretion might be roughly used as a measure of protein metabolism. The 

 belief is probably based on the statements of Zuelzer, although his own 

 tables do not show such constancy, but, on the contrary, show great varia- 

 tion in the ratio. More recent experiments (Buchmann) show that the 

 phosphorus and nitrogen excretion vary quite independently, even on a 

 constant diet (Kellar) ; and the amount of phosphorus metabolized may be 

 much greater than could come from the flesh metabolized. Determination 

 of the ratio of nitrogen to phosphorus in different tissues have been made 

 (Lehman, Muller, Munk, Senator and Zuntz(&), Cronheim and Muller), 

 so that, from the amount of nitrogen excreted in starvation, we can calcu- 

 late the corresponding amount of phosphorus. This has been done 

 (Lehman, Muller, Munk, Senator and Zuntz(6), Kenvall(a)), and there 

 was always a greater excess of phosphorus that must have come chiefly 

 from the bones, since it has been shown that the dry brain and cord, 

 the other phosphorus-rich tissues, do not lose weight in starvation (Voit 

 (a)). Calculation from the data of older results, for example, those of 

 Forster(a), show the same result. 



The Composition of the Bone in Disease. Chemical analyses long ago 

 showed that the amount of mineral matter, and especially the amount of 

 lime salts, in the bone in osteomalacia is decreased. The earliest analysis, 

 a rough one of Bostock, showed but twenty per cent of earthy matter 

 in the bone in a case of this disease. But in this case, and also in the 

 analyses of Marchand, Bogner, Ragsky and von Bibra, the authors did not 

 report their results in such form that they can be compared with later 

 results. That the proportion of inorganic matter is decreased, and that of 

 organic matter increased is shown by Tables 1 and 2, giving the percentage 

 of each in the bone. 



