relations to various exigencies of the Animal Body, \ 59 



produce 100 lbs. increase in live-weight, it was strikingly brought 

 out in all comparable experiments that it was in neither case the 

 amount of nitrogenous constituents, but in both the amount of 

 digestible or available non-nitrogenous constituents (or total or- 

 ganic substance) of the food that had regulated the result obtained. 



Referring the reader to our former papers for all experimental 

 details, and for the fuller discussion of the results and statement 

 of our conclusions, we will close this part of the subject in words 

 quoted from a paper given at the Meeting of the British Asso- 

 ciation at Belfast in ]852*. The sentence as quoted had refer- 

 ence to the results obtained with sheep ; but subsequently those 

 obtained with pigs were summarized in almost the same words : — 



" .... if we consider that it is the results obtained under the 

 subtle agency of animal life that we are seeking to measure and 

 express in figures, and if we also bear in mind the various sources 

 of modification to which our actual figures must be submitted in 

 order to attain their true indications, we think that it cannot be 

 doubted that, beyond a limit below which few, if any, of our 

 current fattening food-stuffs are found to go, it is their available 

 non-nitrogenous constituents, rather than their richness in the 

 nitrogenous ones, that measure both the amount consumed to a 

 given weight of animal, within a given time, and the increase in 

 weight obtained." 



Bearing in mind the nature of the respiratory process, and the 

 great influence which its demands must necessarily exercise over 

 the amount of food consumed, it will scarcely appear surprising 

 that consumption at least should be chiefly regulated by the sup- 

 ply in the food of non-nitrogenous constituents; but that the 

 amount of increase obtained in feeding animals for the butcher 

 should also bear a closer relationship to the supply of the 

 non-nitrogenous than to that of the nitrogenous constituents, 

 might perhaps well be looked upon as inconsistent with the 

 currently adopted views as to the highly nitrogenous character 

 of the increase of animals fed for human food, and, indeed, 

 of the highly nitrogenous character of the animal portion of 

 human food generally. 



The investigation into the composition of the fattening ani- 

 mals, and their increase, above alluded to, showed, however, 

 how small was the proportion of the nitrogenous substance 

 of the food that was stored up in the increase of the animal, 

 and also that the proportion of fat in the increase was much 

 greater than had previously been supposed. The results fur- 

 ther led to the remarkable conclusion, that, reckoning the fat 



* "On the Composition of Foods in relation to Respiration and the 

 Feeding of Animals,' 5 Report of the British Association for the Advance- 

 ment of Science for 1852. 



