PHYSIOLOGICAL EFFECTS OF LABOUR 205 



The increase of energy expended is the corollary of the increase 

 in the material operations of the organs. A greater acidity of 

 the muscles is found after work, and this is attributed (*) to the 

 formation of lactic acid (?), but this acidity is slight in moderate 

 exercise with suitable intervals of repose. In the urine an in- 

 creasing elimination of phosphorus is observed. This is very 

 interesting, because some phosphoretted albumins exist in our 

 cells, and Siegfried attributes to one of them, which is a part of 

 the cellular nucleus, the power to decompose, giving out phos- 

 phorus, carbonic gas and lactic acid ; the centre of those oxy- 

 dations, he says, is this nucleo-proteid,( 2 ) because it decreases in 

 the muscles during work of any duration, whilst their acidity 

 increases. Also the oxydation in organs, rich in nucleo, is ex- 

 tremely intense. ( 3 ) There are, therefore, in the cells certain pro- 

 teid reactions which are only manifested by an excretion of urates, 

 as many experiments have proved. To these same reactions 

 must, no doubt, be attributed the presence in the urine of a pro- 

 teid derivative, creatinine, a derivative which is eliminated when 

 the muscles are contracted statically, and not when they are 

 working. This is an example of the variety of phenomena which 

 take place in living substance, ( 4 ) and of the part played by the 

 proteids in the production of muscular force. 



Work increases the elimination of water by the skin and the 

 lungs, chiefly by perspiration. A subject who, in repose, lost 

 881 grammes of water in this way lost 2,475, 3,230 and even 7,381 

 grammes, after having performed increasingly hard work.( 5 ) 

 A decrease of water in the blood is the result, ( 6 ) accompanied by 

 an irresistible need to restore the loss which gives rise to thirst. 

 The density of the blood is slightly raised. ( 7 ) 



In any study of the phenomena which occur during work we 

 need to give particular attention to the nature of the food so that 

 the proper proportions thereof in fats, proteids, and hydro-carbons 

 may be discovered. 



Metabolism both in repose and during work draws on the 

 proteids in a fairly constant proportion of 60 to 6-5 grammes a 

 day. It affects the carbo-hydrates, since they are the source of 



( x ) Dreser (Centralblatt f. Physiol., vol. i., p. 195, 1887). 

 ( 2 ) Siegfried (Hoppe-Sevler's Zeitsch., vol. xxi., p. 360, 1895-6). 

 ( 8 ) Ralph Lillie (Amer. Journ. of Physiol., vol. vii., p. 412, 1902) ; 

 Bonanni (Arch, di Farm Sper. e Sc. Affini, vol. ii., p. 8, 1902). 



( 4 ) Harkink (C. R. Acad. Sciences d' Amsterdam, 30th Sept., 1911). 

 (*) Atwater and Benedict (Bulletin, No. 136, p. 307 sqq.). 



( 6 ) Kuthy, Zuntz and Schumburg, Lloyd Jones (Journ. of Physiol. , vol. 

 viii., 12). 



( 7 ) Perspiration eliminates a few urates. The material expenditure is 

 0'80 grammes to T40 grammes of proteids per day, which can rise to 

 4 grammes (Atwater). 



