INFLUENCE OF AGE. 365 



consumed far more oxygen during violent bodily exercise than 

 during a state of rest. Prout found that at the commencement of 

 moderate exercise there was a relative excess of carbonic acid in 

 the expired air, but during prolonged violent exercise there was 

 less of this gas than in a state of rest. Vierordt convinced himself 

 that the absolute as well as the relative quantity of carbonic acid 

 was increased after moderate exercise, and this result is in perfect 

 conformity with the experiments of Scharling. H. Hoffmann* 

 found that the sum of the products of perspiration of the skin and 

 lungs was much more considerable after prolonged motion than 

 after prolonged rest. Every one who has instituted experiments 

 on the respiration of animals must be aware that they expire far 

 more carbonic acid when they are lively and active than during a 

 state of repose. 



Scharling's observations do not entirely exclude the suppo- 

 sition that mental exertion may induce an augmented excretion of 

 carbonic acid. 



The experiments instituted on man and animals, with the view 

 of ascertaining whether age exerts any influence on the respiration, 

 prove that considerable weight should be attached to this relation. 

 Andral and Gavarret, who made tolerably complete observations 

 on the absolute quantity of exhaled carbonic acid, found that the 

 quantity daily expired increases, on an average, to the 40th or 

 45th year, agreeing mainly with the development of the muscular 

 system. In Scharling's experiments, the two children experi- 

 mented upon (one a boy aged 9J years, and the other a girl of 

 the age of 10 years) expired almost double the amount of carbonic 

 acid exhaled by adults, if we calculate the excretion of carbonic 

 acid for an equal bodily weight ; but where the latter is not con- 

 sidered, we find that Scharling's results agree perfectly with those 

 of Andral and Gavarret. The observations made by Regnault and 

 Reiset on animals are also in accordance with these experiments 

 on man, for it was shown that in animals of the same species, for 

 equal weights, more oxygen was consumed by young than by adult 

 animals. 



With regard to the influence of sex on respiration, it appears, 

 from the experiments of Scharling as well as from those of Andral 

 and Gavarret, that males expire more carbonic acid than females 

 a relation which obtains even in childhood, for boys eliminate 

 more carbonic acid than girls. 



As Scharling's observations must, for the present, to a certain 

 * Ann. d. Ch. u. Pharm. Bd. 45, S. 242. 



