3 88 



THE POPULAR SCIENCE MONTHLY. 



matures, the mineral, the nitrogenous, and the fatty matters all in- 

 crease in actual amount ; but the percentage of both mineral matter 

 and nitrogenous substance decreases, while that of the fat increases so 

 as to much more than compensate for the decrease in that of the other 

 solid matters. The result is that there is an increase in the percentage 

 of total dry substance." The young animals, as the lamb and calf, 

 had a larger proportion of water in the carcass than other animals in 

 the same condition ; and there was a larger proportion of bones in the 

 carcass of the calf than in the carcass of the other animals. 



In estimating the composition of the increase in live weight of fat- 

 tening animals it was assumed that the composition of the original 

 weight, that is, the weight at the beginning of the feeding period, 

 was the same as in the "store" or "half- fat" animals that had been 

 analyzed ; and that the composition of the animal at the close of the 

 feeding period was the same as that of the " fat " or the " very fat " 

 animal that had been analyzed. By a proper exercise of judgment as 

 to the comparative condition and quality of the animals at the begin- 

 ning and end of the feeding period, and applying the data derived 

 from the analysis of animals of similar quality, a close approximation 

 to the composition of the increase could thus be obtained, and the 

 probable error would be reduced to a minimum when the averages 

 were made up from a large number of animals. In this way the com- 

 position of the increase was estimated in the case of ninety-eight fat- 

 tening oxen, three hundred and forty-nine fattening sheep, and eighty 

 fattening pigs, divided into numerous classes according to breed, con- 

 dition of maturity, and description of food consumed. The estimated 

 average percentage of mineral matters, nitrogenous substance, fat, and 

 total dry substance, in the increase of these animals, is given in the 

 following table : 



The averages of all the animals under experiment, fed under a 

 variety of conditions, and including the " fat " and the " very fat," are 

 here given. In the tables which follow, however, data from selected 

 cases are made use of, which do not change the general results, but 

 represent, it is believed, more nearly, the results obtained in ordinary 

 farm practice. 



The percentage of mineral constituents in the increase of the sheep 

 as given in the table is undoubtedly too high, from the presence of 

 foreign matters in the wool which could not well be separated ; this 



