PART IV.] Carbonaceous Material the Basis of Muscular Motion. 643 



teaching, the leading object which has been ordinarily kept in view in the con- 

 struction of dietaries has been to increase the nitrogenous elements in the food 

 proportionately, and this in a somewhat arbitrary fashion, to the amount of work exacted. 



6. On the strength of this doctrine it has frequently been assumed that the 

 working population of this country, and especially the rice-consuming portion of it, 

 is under-fed, seeing that the amount of albuminous material which enters into their 

 ordinary food is evidently far too small to compensate for the waste of the muscular 

 tissue which the work they perform was supposed to entail. The great distance which 

 a palanquin-bearer, for example, will often travel on food containing an extremely 

 small proportion of nitrogenous material has astonished many European observers, the 

 quantity of albuminates in his food being quite inadequate to replace the waste of 

 muscle which, it was supposed, must have taken place in carrying himself and his 

 burden. Every-day experience in this country, therefore, seemed to contradict the 

 doctrine that physical labour and destruction of the nitrogenous muscular tissue should 

 be looked upon as almost synonymous. 



7. This experience is quite in accord with the teachings of the leading physiologists 

 of the present day. In opposition to Liebig, who admitted that the heat but not the 

 motion of the body was due to the oxidation of combustible matters, J. E. Mayer (so 

 far back as 1845) maintained that the chemical force contained in the ingested food 

 and in the inhaled oxygen was the source of the motion as well as of the heat. The 

 truth of this statement has been confirmed by many observers, and during recent 

 years Mayer's researches have been greatly extended. Conspicuous amongst these 

 researches are the experiments which have been made on men and animals by 

 Professors Pettenkofer and Voit, and which, amongst other things, have conclusively 

 demonstrated that the amount of nitrogen excreted by the body during rest is so 

 nearly the same as during exertion that the possibility of power being dependent on 

 nitrogenous waste is, virtually, excluded. These observations, and many others of a 

 like character,* have a very practical significance as regards the question of the most 

 suitable dietary for a labouring population, and it would clearly be a mistake to 

 continue formulating scales of diet based on a doctrine which is no longer tenable. 



8. Indeed, the present tendency is to invert the doctrine of Liebig, and to hold 

 that it is carbonaceous and not nitrogenous material which is chiefly consumed during 

 mechanical action. In a recent lecture delivered before the British Association, Pro- 

 fessor Burdon-Sanderson says : — " In what may be called ' commercial physiology,' the 

 physiology of trade puffs, one still meets with the assumption that the material basis 

 of muscular motion is nitrogenous ; but by many methods of proof it has been shown 

 that the true Oel in der Flamme des Lebens is not proteid [or albuminoid] substance 

 but sugar or sugar-producing material."! Although, according to the most recent 



* A very carefully prepared account of the principal of these will be found in Chapter IX of Gamgee's 

 Physiological Chemistry of the Animal Body. — Vol. I, 1880. 

 t Nature, September 8th, 1881, page 440. 



