432 RESPIRATION. 



Taking into consideration the increase in the weight of 

 the body with age, it is evident that the respiratory activity 

 is much greater in youth than in adult life. Andral and 

 Gavarret do not give the weight of the subjects of their 

 observations, but as the weight generally does not diminish 

 after maturity, there can be no doubt that there is a rapid 

 diminution in the relative quantity of carbonic acid produced 

 in old age. 



Scharling, in a series of observations on a boy nine years 

 of age, weighing 48*5 pounds, an adult of twenty-eight, and 

 one of thirty-five years, the latter weighing 163'6 pounds, 

 showed that the respiratory activity in the child was nearly 

 twice as great, in proportion to his weight, as the average in 

 the adults. 1 It is seen from the observations of Andral and 

 Gavarret, that the absolute increase in the exhalation of car- 

 bonic acid from childhood to adult life is very slight in com- 

 parison with the natural increase in the weight of the body ; 

 showing that, proportionately, the exhalation of carbonic acid 

 is greater in early life. 



Influence of Sex. All observers have found a marked 

 difference between the sexes, in favor of the male, in the 

 proportion of carbonic acid exhaled. Andral and Gavarret 

 noted an absolute difference of about forty-five cubic inches 

 per hour, but did not take into consideration the difference 

 in the weight of the body. Scharling, taking the proportion 

 exhaled to the weight of the body, noted a marked difference 

 in favor of the male. 



The difference in the degree of muscular activity in the 

 sexes is sufficient to account for the greater evolution of car- 

 bonic acid in the male, for this principle is exhaled in pro- 



1 SCHARLING, Recherckes sur la Quantited'Acide Carbomque expire par Fffomme. 

 Annales de Chimie et de Physique, 3me serie, torae viii., p. 486. 



Taking the proportion of carbonic acid exhaled per hour to the weight, in 

 the man 28 years of age, as 1, in the man 35 years of age the proportion was 1'14, 

 and in the boy 9| years of age, 2-07. P. 489. 



