SCIENTIFIC FARMING AT ROTHAMSTED. 387 



slaughtered at once, and its contents of nitrogenous substance, fat, 

 mineral matter, etc., accurately determined. The other was fed on a 

 mixture consisting of bean-meal, lentil-meal, and bran, each one part, 

 and barley-meal three parts, given ad libitum, but accurately weighed, 

 for a period of ten weeks, when it had nearly doubled its weight. The 

 animal was then slaughtered, and analyzed as the other had been. The 

 composition of the food was also determined by analysis." 



According to the generally accepted theory of nutrition at the time 

 the Rothamsted feeding experiments were planned, the constituents 

 of foods were divided into two leading groups, each of which was 

 assumed to serve a special purpose in the system. It was believed 

 that the nitrogenous constituents were the only nutritive elements, 

 and that the carbonaceous constituents (including the fat, starch, etc.) 

 served as fuel, which was burned in the system to keep up the animal 

 heat. In the published analyses of animals and of foods at Rotham- 

 sted, this distinction was recognized, and the results are given in terms 

 of these groups of constituents. A summary of the results of the 

 analyses of the ten animals described above is given in the following 

 table, in percentage values of groups of constituents, in the carcass 

 and in the total offal parts : 



This table furnishes some important data for an intelligible discus- 

 sion of the economics of nutrition, with reference to human dietaries, 

 but there are many points of interest presented in the details of the 

 analyses of these animals that can not be embraced in such a tabular 

 abstract. In the carcass of the fat calf, it will be noticed, the per- 

 centage of nitrogenous substance and of /at is the same, while in the 

 other animals the fat is largely in excess, even in those in store con- 

 dition. There is likewise a larger percentage of nitrogenous substance 

 in the offal parts than in the carcass in all cases. It was also found 

 that < the fat of the bones bears but a small proportion to that of the 

 whole carcass, while, of the whole of the nitrogen of the carcasses, 

 perhaps not less than one fifth will be in the bones. . . . As the animal 



