VII. The influence of bodily labour upon the discharge of nitrogen

The scope of this inquiry has been strictly limited to one question, viz., that of the influence of labour in modifying the normal relation between food and excreta. No attempt has been made to investigate themode in which nitrogenous products come into existence in the organism. The researches immediately bearing on the subject of this paper are those of Dr. Parkes (“Proc. Roy. Soc.,” vols. 16 and 21), and those of Dr. Austin Flint, made on the pedestrian Weston (“New York Med. Journal,” June, 1871). Dr. Parkes found that bodily exercise caused a slight increase in the nitrogen discharge during or immediately after labour. The increase was, however, so inconsiderable that it may well be questioned whether it could not be accounted for as dependent on the more perfect absorption of food; for although the diet of the soldiers experimented upon was carefully regulated, and the nitrogen it contained determined by analysis, with the result that before work the quantity of nitrogen taken in considerably exceeded the quantity discharged, the two became practically equal during the work period. Consequently if the whole period of observation is taken into account, the nitrogen discharged is found to be more than balanced by that of the food.