386 THE POPULAR SCIENCE MONTHLY. 



animals, the range of variation being but little more than one half of 

 one per cent. It should be stated that the much smaller percentage 

 of offal parts, and the corresponding larger percentage of carcass, in 

 the pigs, is partly to be attributed to the head and legs being included 

 with the carcass of the pigs, while they are reckoned as offal parts in 

 oxen and sheep. With sheep there was a rapid decrease in the per- 

 centage of offal parts as the animals fattened, while the percentage of 

 carcass increased from 53*4 in the store condition to 64*1 in the very 

 fat condition. There was, however, an actual increase in the offal 

 parts from the store to the very fat condition in the proportion of one 

 to one and three quarters, but the carcass parts made a greater actual 

 increase, one pound in the store condition being raised to two and one 

 half pounds in the very fat condition. 



In connection with the data furnished by the mass of facts relating 

 to the relative proportion of organs and parts of the body, which we 

 can not discuss in detail, it became a matter of interest to ascertain 

 the chemical composition of the increase of fattening animals obtained 

 from different articles of food, so that the relations of the food con- 

 stituents to the constituents of the increase coidd be determined. As 

 a chemical analysis of a living animal can not be made, it is of course 

 impossible to determine directly the chemical composition of the in- 

 crease, as an analysis would be required at the beginning and at the 

 close of the fattening period. The composition of the increase of 

 fattening animals must therefore be determined by indirect methods, 

 as by calculation from the data furnished by the differences in the 

 composition of the food and the excretions ; or from assumed con- 

 stants, in the form of averages obtained by analyzing a large number 

 of representative animals. 



The most satisfactory data relating to this subject, that have ever 

 been published, will be found in the results of the numerous analyses 

 of the entire bodies and parts of animals, in different conditions a3 

 to fatness, that have been conducted at Rothamsted. Determinations 

 were made of the fat, nitrogenous substance, and mineral matter of 

 the entire body, and of certain separated parts, of ten animals, de- 

 scribed as follows : 1. A fat calf, of the shorthorn breed, nine or ten 

 weeks old, taken from its dam, feeding on grass ; 2. A half-fat Aber- 

 deenshire ox, about four years old, fed on fattening food, but which 

 had grown rather than fattened ; 3. A moderately fat Aberdeenshire 

 ox, about four years old ; 4. A fat Hampshire Down lamb, about six 

 months old ; 5. A Hampshire Down store sheep, about one year old ; 



6. A half-fat Hampshire Down ewe, three and one fourth years old ; 



7. A fat Hampshire Down sheep, one and a fourth year old ; 8. A 

 very fat Hampshire Down sheep, one and three fourths year old ; 9. 

 A store pig ; 10. A fat pig. The pigs were of the same litter, and, 

 when selected, were as nearly as possible alike, one weighing one hun- 

 dred pounds and the other one hundred and three pounds. " One was 



