292 



THE ROTHAMSTED EXPERIMENTS. 



Results 

 liable to 

 correction. 



Nitrogen- 

 ous sub- 

 stance 

 again in 

 excess. 



Appropri- 

 ate food 

 for pigs. 



It is next seen, that the 100 of increase was estimated to 

 contain 63.1 parts of fat, whilst the food supplied only 15.6 

 parts, leaving therefore, at least, 47.5 parts to be produced 

 within the body. The figures show that this would require 

 36.6 parts of carbon, whilst 44.0 parts are estimated to have 

 been available from the nitrogenous substance of the food ; 

 leaving, therefore, according to the mode of calculation 

 adopted, 7.4 parts more carbon available than were required 

 for the formation of the produced fat. Or, as shown in the 

 bottom division of the table, for 100 carbon in the estimated 

 newly formed fat, 120.2 parts were available from the nitro- 

 genous substance consumed in the food. 



Here, then, the calculations afford no evidence that fat 

 must have been produced from carbohydrates. But, as already 

 explained, the mode of estimate adopted assumes the whole of 

 the ready-formed fat in the food to have been stored up, and 

 the whole of the carbon of the nitrogenous substance, beyond 

 that in the animal increase, and in the urea formed, to have 

 been utilised for fat formation. Neither of these assumptions 

 is, however, admissible ; and it will be seen further on, when 

 due correction is made in regard to these points, that, even in 

 this experiment, with so abnormally high a proportion of 

 nitrogenous substance in the food, it is pretty certain that 

 some of the produced fat must have had its source in the 

 carbohydrates. 



In experiment 2, the food consisted of bean-meal, lentil- 

 meal, bran, and maize-meal, each given separately, and ad 

 libitum ; and in experiment 3, of an equal mixture of bean- 

 meal and lentil-meal, also given ad libitum. It is seen that, 

 in both cases, the proportion of crude non-nitrogenous to 1 of 

 crude nitrogenous substance in the food was even lower than in 

 experiment 1 ; being, in experiment 2, 3.3, and in experiment 

 3, only 2.0, against 3.6 in experiment 1. Here again, as 

 might be expected, with so high a proportion of nitrogenous 

 substance in the food, the calculations show that there was 

 more than sufficient carbon available from the nitrogenous 

 substance of the food for the formation of all the fat that was 

 estimated to be produced. 



Experiments 4 and 5 show a very different result. In 

 experiment 4, the food consisted of maize-meal alone, and in 

 experiment 5 of barley-meal alone, in each case given ad 

 libitum. In America especially, maize-meal is largely used 

 for the fattening of pigs, almost, if not quite alone ; and in 

 our own country barley-meal is undoubtedly recognised as 

 the most appropriate fattening food of the animal. It is seen 

 that, in experiment 4, with maize-meal, the proportion of 

 crude non-nitrogenous to 1 of nitrogenous substance in the 



