532 iiKPOKT — IS 80 



Baud viii. 1879, Supplement) has applied the same mode of calculation to results ol>- 

 tained by liimself with pigs some years ago. He concluded that the "whole of the body 

 fat could not have been formed without the direct co-operation of the carbo-hydrates 

 of the food. But what is of greater interest still is, that he also calculated, in the 

 same way, the results of some then quite recent experiments of Henneberg, Kern, 

 and Wattenberg, with sheep. He thus foimd that, even including the whole of the 

 estimated amides with the albumin, there must have been a considerable production 

 of fat from the carbo-hydrates ; and, excluding the amides, the amount reckoned to 

 be derived from the carbo-hydrates was of course much greater. 



I will only add, on this point, that, on re-calculating some of our early results 

 with sheep, which did not afford sufficiently conclusive evidence when the whole of 

 the nitrogen of the food was reckoned as albumin, these show a very considerable 

 formation of fat from the carbo-hydrates, if deduction be made for the probable 

 amount of non-albuminoid nitrogenous matter of the food. 



We have now, then, the two agricultural chemists of perhaps the highest 

 authority, both as experimenters and writers on this subject on the Continent, 

 giving in their adhesion to the view, that the fat of the herbivora, which we feed 

 for human food, may be, and probably is, largely produced from the carbo-hydrates. 

 I dare say, however, that some physiologists will not change their view until Voit 

 gives them sanction by changing his, which, so far as I know, he has not yet done. 

 The question whicli has been currently entitled tliat of ' The Origin of Muscidar 

 Power,' or ' The Sources of Muscular Po^ver,' has also been the subject of much 

 investigation, and of much conflict of opinion, since the first publication of Liebig's 

 ■views respecting it in 1842. 



As I have already pointed out, he then maintained that the amoimt of muscular 

 tissue transformed, the amoimt of nitrogenous substance oxidated, was the measure 

 of the force generated in the body. He accordingly concluded that the requirement 

 for the nitrogenous constituents of food would be increased in proportion to the in- 

 crease of the force expended. In his more recent writings on the subject, he freely 

 criticises those who take an opposite \-iew. He nevertheless grants that the secretion 

 of urea is not a measure of the force exerted ; but, on the other hand, he does not 

 commit himself to the admission that the oxidation of the carbo-hydrates is a source 

 of muscular power. 



The results of our own early and very numerous feeding experiments were, as 

 has been said, extremely accoi'dant in showing that, pro\'ided the nitrogenous con- 

 stituents in the food were not below a certain rather limited amount, it was the 

 quantity of the digestible and available non-nitrogenous constituents, and not that 

 of the nitrogenous substance, that determined — botli the amount consumed by a given 

 live-weiqht within a given time, and the amount of increase in live-weight 2froduced. 

 They ako showed that one animal, or one set of animals, might consume two or 

 three times as much nitrogenous substance in proportion to a given live-weight 

 within a given time as others in precisely comparable conditions as to rest or exercise. 

 It was further proved that they did not store up nitrogenous subtance at all in 

 proportion to the greater or less amoimt of it suppHed in the food, but that the 

 excess reappeared in the liquid and solid matters voided. 



So striking were these results, that we were led to turn our attention to human 

 dietaries, and also to a consideration of the management of the animal body under- 

 going somewhat excessive labour, as, for instance, the himter, the racer, the 

 cab-horse, and the foxhound, and also pugilists and runners. Stated in a very few 

 words, the conclusion at which we arrived from these inquiries (which were sum- 

 marised in our paper given at Belfast in 1852) was — that, unless the system were 

 overtaxed, the demand induced by an increased exercise of force was more charac- 

 terised by an increased requirement for the more specially respiratory, than for the 

 nitrogenous, constituents of food. 



Soon aftei-wards, in 1854, we found by direct experiments with two animals in 

 exactly equal conditions as to exercise, both being in fact at rest, that the amount 

 of urea passed by one feeding on highly nitrogenous food was more than twice as 

 great as that fed on a food comparative^ poor in nitrogen. 



It was clear, therefore, that the rule which had been laid down by Liebig, and 



