71 



cent as tbe minimum, a difference of little over 5 per cent. The difficulty 

 of comminuting the bones into a homogeneous mass, and thus securing 

 an average sample, probably accounts for a great deal of the discrepancy 

 seen in the summations of the analyses. It is evident that the bones 

 contain a very large amount of nutrient matter which would be avail- 

 able for digestion if they were sufficiently comminuted; since the ash 

 consists almost exclusively of tricalcium phosphate, which is insoluble, 

 and thus would not interfere greatly with the process of digestion. 

 The bones of animals, however, are so valuable for fertilizing purposes 

 that they have not been used to any extent for feeding, except for 

 poultry. 



Average of marrow. Table 11 contains the average analyses of the 

 samples of marrow from all the bones from each cut of each aniinal r 

 except in the case of Duroc Jerseys, Nos. G and 7, where the samples of 

 marrow were destroyed by mice. On account of the small amount of 

 material at our disposal, the ash in the samples was not determined. 

 The summation, therefore, represents only partially the total ingre- 

 dients, since it does not include the ash nor the lecithin, which are 

 very important components of the marrow substance. The marrow, as 

 will be seen by the data, is essentially a fat product, more than 95 per 

 cent of the whole weight of the material being composed of fat and 

 water, the mean percentage of fat in the whole sample being 81.13, and 

 of water, 1J.57. The nitrogenous constituents of the marrow, while 

 being extremely important from a physiological point of view, have not 

 much value from a nutritive point. They constitute only 2.29 per cent 

 of the whole. There is a fairly good concordance seen in the composi- 

 tion of the marrow from the different animals. In point of fat, the 

 greatest variations are found in case of the Tamworth, with a maxi- 

 mum percentage of fat, and the Poland China, with a minimum per- 

 centage, the difference being, in round numbers, 16 per cent. The 

 variations in water are less marked, while in the total nitrogenous 

 matters only one, namely, the Tamworth, falls far below the others in 

 the percentage contained. The summation is as good as could be 

 expected, considering the fact that ingredients of considerable magni- 

 tude are omitted. 



Average of skin. Table 12 contains the average analytical data for 

 the skin of all of the cuts of each animal. All the skin from each ani- 

 mal was mixed together arid carefully comminuted by passing several 

 times through a meat chopper until a homogeneous mass was obtained. 

 From this mass a suitable sample was taken, representing as nearly as 

 possible the average composition of the whole. On this were performed 

 the analytical operations from which the data represented in Table 12 

 were secured. The table contains the analytical data for all the ani- 

 mals except No. 8, the Yorkshire, of which the sample was lost. The 

 most remarkable fact in connection with a general view of the data is 

 that the skins have a high rank among the nitrogenous substances of 



