502 Influence of Labour upon the Discharge of Nitrogen. 



regarded as a mere exaggeration of this tendency, and not as a new 

 process which is set up in the living tissue to compensate for a pre- 

 vious disturbance. 



In this, as in other respects, it is obvious that the knowledge which 

 has been gained is only partial. 



If, with a nitrogenous income of 17'6 grams per diem, accumu- 

 lation takes place under normal conditions of life, the minimum 

 adequate supply of nitrogen must be below this. We have no means 

 of stating at present what this adequate supply is, but we have 

 reason to believe that it would be found to differ materially in dif- 

 ferent individuals, and in the same individual in different states of 

 health. If we could ascertain to what point the supply of nitrogen 

 in any individual could be diminished, without drawing upon his 

 store of nitrogenous material, we should have in this result a perfectly 

 reliable chemical criterion of what may be termed nutritive vigour. 



No attempt has hitherto been made to carry out such observations 

 on the human subject, nor do any experimental data exist which 

 would justify even a guess at what the results of a properly conducted 

 investigation would be. 



What is first required is to ascertain for how long and in what 

 quantity nitrogen continues to be stored on the diet already men- 

 tioned, the period of observation to be at least a fortnight. This 

 having been accomplished, the next step would be to repeat the 

 observation with diets containing less nitrogen than the amount 

 above stated, but otherwise similar to it. 



We should then be in a position to inquire how far the increase of 

 nitrogenous output, which has been shown to be the immediate 

 result of labour, is dependent on previous storage, and whether, in 

 conditions of nutrition which involve absence of storage, the effect 

 of severe labour manifests itself in an increased discharge, and finally 

 whether in this case such work can be undergone without producing 

 other disturbances. 



A collateral inquiry, which is scarcely less necessary than that 

 which has just been indicated, must as soon as possible be under- 

 taken as to the effect of varying the relation between the time at 

 which food is taken and that at which the work is done. 



It has not yet been possible to attempt to enter on this inquiry, 

 which obviously could not be combined with any other. Its import- 

 ance lies in this, that it would, if successful, afford information as 

 to the question whether or not the organism is capable of at once 

 applying the nitrogenous material of food to meet increased expen- 

 diture determined by work. 



In the investigations hitherto conducted by me the work done has 

 consisted exclusively of walking. At a future period I hope to sub- 

 stitute other methods of labour, the employment of which will render 



