EXHALATION OF CARBON DIOXIDE 123 



during complete repose, 24,208 cubic inches (about 14.24 cubic feet, or 

 336.145 liters), containing 7.144 ounces (202.47 grams) of carbon. In 

 view of the great variations in the exhalation of carbon dioxide, this 

 estimate can be nothing more than an approximation. 



One of the important modifying influences is muscular exertion, by 

 which the production of carbon dioxide is largely increased. This would 

 indicate a large quantity during ordinary conditions of exercise, and a 

 much larger quantity in the laboring classes. Dr. Smith has given the 

 following approximate estimates of these differences: 



Inquietude 7- r 44 ounces (202.47 grams) of carbon. 



Non-laborious class 8.68 ounces (246.04 grams) of carbon. 



Laborious class 11.7 ounces (331.61 grams) of carbon. 



Influence of Age. During the first few days of life, the infant does 

 little more than sleep and take the small quantity of colostrum furnished 

 by the mammary glands of the mother. While the animal functions 

 are so imperfectly developed and until alimentation becomes more abun- 

 dant and the infant begins to increase rapidly in weight, the quantity of 

 carbon dioxide exhaled is very small. After the respiratory function has 

 become fully established, it is probable, from the greater number of respi- 

 ratory movements in early life, that the production of carbon dioxide, in 

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

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

 point. 



The observations of Andral and Gavarret show the comparative ex- 

 halation of carbon dioxide in the male, between the ages of twelve and 

 eighty-two, and give the results of a single observation 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. 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, and there can be no doubt that there is a rapid 

 diminution in the relative quantity of carbon dioxide produced in old age. 

 Scharling, in a series of observations on a boy nine years of age, an adult 

 of twenty-eight and one of thirty-five years, showed that the respiratory 

 activity in the child was nearly twice as great, in proportion to his weight, 

 as the average in the adults. 



Influence of Sex. All observers have found a notable difference be- 

 tween the sexes, in favor of the male, in the proportion of carbon dioxide 

 exhaled. Andral and Gavarret noted an absolute difference of about 

 forty-five cubic inches (737.4 cubic centimeters) per hour, but did not 



