600 



PROCEEDINGS OF SECTION G". 



reasons for attributing the prevalence of the disease to the usual diet 

 of such animals in South Africa — viz., a diet composed solely of 

 cereals. 



From an examination of the bones of a large number of animals, 

 some of which had died from the disease, while others were free from 

 it, he found that it was quite possible to classify the bones into those 

 of diseased and those of healthy animals. 



The most striking method was to take the ratio of nitrogen 

 (really a measure of the amount of ossein present) to the ash in the 

 bones, thus eliminating the influence of the varying amount of fat 

 left in the sample. 



With the bones of healthy animals, the ratio was found to vary 

 from 1: 13-5 to 1:15'6, and to have an average value of 1 : li'ST. 

 In the case of the diseased animals, the ratio varied from 1 : 9*8 to 

 1 : ll'T, the mean value being 1 : 10-8. 



In tabulating the results, and considering the possible causes 

 which might lead to such a condition, the writer eventually concluded 

 that it was to the peculiar diet of working animals in South Africa — 

 as already mentioned, one consisting entirely of cereals — viz., oaten 

 hay, or oaten hay and maize — that the prevalence of the disease was 

 due, and that the real cause was the high ratio of phosphorus pent- 

 oxide to lime in the ash of such a diet. 



The most desirable ratio of phosphorus pentoxide to lime in the 

 whole ration of animals in order to favour bone formation and renewal 

 has not been directly detemiined, but some deductions may be made 

 from a study of the composition of the whole body of animals, and 

 of the natural food of young animals — viz., milk. 



In bone itself the ratio is about 100 of phosphorus pentoxide to 

 150 of lime, but it must be remembered that some of the phosphorus 

 found as phosphates in the ash of the whole bodies of animals is 

 present in the form of organic matter — e.g., in the brain and in 

 lecithin. 



In the Rothamsted experiments it was found that 1,000 lb. of 

 the whole bodies of animals contained the following amounts of 

 phosphorus pentoxide and lime: — 



P2O5 : CaO. 



100 



108 

 116 

 lU 

 112 

 107 

 ■95 



In all cases but the last it will be n(>ticed that the amount of 

 lime is greater than that of phosphorus pentoxide. 



