INFLUENCE OF AGE. 431 



Influence of Age. In treating of the consumption of 

 oxygen, it was stated that during the first few days of extra- 

 uterine existence, the demand for oxygen on the part of the 

 system is very slight. At this period there is a correspond- 

 ingly feeble exhalation of carbonic acid. It is well known 

 that during the first hours and days after birth the new 

 being has little power of generating heat, needs constant 

 protection from changes in temperature, and the volun- 

 tary movements are very imperfect. During the first few 

 days, indeed, the infant does little more than sleep and take 

 the small quantity of colostrum which is furnished by the 

 mammary glands of the mother. While the animal functions 

 are so imperfectly developed, and until the nourishment be- 

 comes more abundant and the child begins to increase rapidly 

 in weight, the quantity of carbonic acid exhaled is very small. 



After the respiratory function becomes fully established, 

 it is probable, from the greater number of respiratory move- 

 ments in early life, that the production of carbonic acid, in 

 proportion to the weight of the body, is greater in infancy 

 than in adult life. Direct observations, however, are wanting 

 on this point. 



The observations of Andral and Gavarret * show the com- 

 parative exhalation of carbonic acid in the male, from the age 

 of twelve to eighty-two, and give the results of a single obser- 

 vation at the age of one hundred and two years. They show 

 an increase in the absolute quantity exhaled from the age of 

 twelve to thirty-two ; a slight diminution from thirty-two to 

 sixty ; and a considerable diminution from sixty to eighty- 

 two. These results are given in the following table : 



Carbonic acid exhaled per Tiour. 



In boys from twelve to sixteen years 915 cubic inches. 



In young men from seventeen to nineteen years 1,220 " " 



In men from twenty-five to thirty-two years 1,343 " " 



In men from thirty-two to sixty years 1,220 " " 



In men from sixty-three to eighty-two years 933 " " 



In an old man of one hundred and two years 671 " * 



1 Loc. cit. 



