26 



ARON. 



young dogs of the same litter, at a time when they were of different 

 weights and different ages. These animals (C and D) were of equal 

 weight at the time I) was killed and analyzed. Dog C was then fed 

 normally for about seventy-five days and analyzed. These results show: 



Live iveight and iveight of nine bones, dogs D, G, and V. 



Dog. 



Live 

 weight. 



Weight of 

 9 corre- 

 sponding 

 bones. 



Per cent 

 of live 

 weight. 



D 



Grams. 

 1,985 

 3,410 

 5,885 



Grams. 



47.0 



81.6 



127.0 



2.37 

 2.39 

 2.16 



C 



V 





The weights of the corresponding bones expressed as percentages 

 of the respective liVe weights are nearly the same in dogs D, C, and V. 

 We may assume that in dog VI, which vpas kept at constant w^eight, 

 these bones amounted to about 2.2 per cent of its live weight before 

 the experiment began. Hence, on or about the first day of the experi- 

 ment, when the animal weighed 3,200 grams, these nine bones had a 

 weight of about 70 grams. After about two hundred days, the same 

 animal weighed 2,800 grams only, and the bones had increased in weight 

 to 119 grams. 



The composition of a normal dog is approximately constant (Voit,^* 

 Pfeiffer,^^ Stockhausen ^''), the skeleton 15 per cent, the muscles (flesh) 

 50 per cent of the live weight. The skeleton plus fiesh of our normal 

 dog V was found to equal 65.2 per cent of the live weight, which is in 

 very close agreement with these figures. We are justified in regarding 

 15.0 per cent as skeleton, 50.2 per cent as flesh, 65.2 per cent skeleton 

 and flesh. 



The entire skeleton therefore would weigh 883 grams. Now, if 

 we know that the same fraction of fresh bones, which in dog V weighed 

 127 grams, was 119.4 grams in dog VI, we can apply the results obtained 

 with the nine Ijones to the entire skeleton, as follows : 



883X119.4 

 127 



:830 grams. 



^*Ztschr. f. Biol. (1894), 30, 510-522. 

 ''Ibid. (1887), 23, 340-380. 

 ^"Biochem. Ztschr. (1909), 22, 244. 



