288 THE ROTHAMSTED EXPERIMENTS. 



less proportion of alimentary organs and contents ; he con- 

 sumes more food in proportion to his weight; he yields a 

 larger proportion both of total increase and of fat ; and fin- 

 ally, much less of his food is effete and voided. The general 

 result is, that changes in his live- weight are in a much less 

 proportion influenced by variations in the contents of the ali- 

 mentary organs, and are, therefore, much truer indications 

 of change in the substance of the body ; and hence the range 

 of error in calculating the amount and composition of his 

 increase in relation to the amount and composition of the 

 food consumed, is much less. 



The Experiments at Bothamsted with Pigs. 



In the selection of the experiments with pigs, for calculat- 

 ing whether more fat was stored up than could possibly have 

 been derived from the ready-formed fat and the nitrogenous 

 substance of the food, some have been taken in which the 

 proportion of the nitrogenous to the non-nitrogenous constitu- 

 ents of the food was abnormally high, and others in which it 

 was fairly normal, or even low. In all cases, the experiments 

 were conducted for periods of not less than eight or ten 

 weeks ; and the amounts, both of total increase, and of fat 

 stored up, were so large in proportion both to the original 

 weight of the animal, and to the amount of food consumed, 

 that the data obtained may safely be relied upon for the 

 settlement of the question at issue. 

 Table 70 In the upper portion of the next Table (70) are recorded 



explained. some particulars of the nine experiments selected for calcula- 

 tion — namely, the description of the food, the number of 

 animals experimented upon, the duration of the experiment, 

 the original and final live- weights, the increase per head and 

 on 100 original weight, the percentage of carcass in fasted 

 live-weight, and the amount of crude non-nitrogenous to 1 of 

 crude nitrogenous substance in the food. 



The middle division of the table shows, for 100 increase in 

 live-weight — the amount of nitrogenous substance consumed 

 in the food, the amount of it estimated to be stored up in the 

 increase, and the quantity remaining, and therefore possibly 

 available for the formation of fat. Next, there are given — 

 the estimated amount of fat in the increase, the amount 

 ready-formed in the food, and the difference — that is, the 

 amount newly-formed. There are then given — the amounts 

 of carbon in the estimated newly-formed fat, the amounts in 

 the available nitrogenous substance minus that in the urea 

 formed, supposing the whole of the nitrogen not stored up in 

 increase to contribute to such formation ; and lastly, the dif- 



