584 



OF RESPIRATION. 



A Canary - 

 A Turtle-Dove 

 Two Mice - 

 A Guinea-Pig 



Temp, about 32. 

 Grammes. 

 0-325 

 0-974 

 0-531 

 3-006 



Temp. 59 68. Temp. 86 106. 

 Grammes. Grammes. 



0-250 0-129 



0-684 0-336 



0'498 0-268 



2-080 1-453 



From this table it appears that the quantity of carbonic acid exhaled by Mammals between 

 86 and 106 is less than half that set free near the freezing-point; whilst that which is 

 exhaled between 59 and 68 is but little more than two-thirds of the same amount. The 

 diminution occasioned by heat is still more remarkable in Birds; which exhaled at the 

 highest temperature scarcely more than one-third of that set free at the lowest. The ob- 

 servations of Vierordt upon himself show that the same is true of the Human subject ; a 

 difference of 10 Fahr., according to him, producing a variation of rather more than two 

 cubic inches in the amount of Carbonic Acid hourly expired. 



b. Jlge. The amount of Carbonic Acid exhaled increases in both sexes up to about the 

 thirtieth year; it remains stationary until about the forty-fifth ; and then diminishes. The 

 following are the comparative results of experiments upon males of different ages, and of a 

 moderate degree of muscular development (Andral and Gavarret). 



Age. 



8 years 

 12 " 

 14 " 

 20 " 

 26 " 



Carbon exhaled 

 per hour. 

 77-0 grains 



- 113-9 " 



- 126-2 " 



- 166-3 " 



- 169-4 " 



Age. 

 37 years 



48 " 

 59 " 

 68 " 

 76 " 



Carbon exhaled 



per hour. 

 164-7 grains. 



- 161-7 " 



- 154-0 " 



- 147-8 " 



92-4 " 



c. Sex. At all ages beyond eight years, the exhalation is greater in Males than in Fe- 

 males. Nearly the same proportionate increase takes place, however, in females, up to the 

 time of puberty; when the quantity abruptly ceases to increase, and remains stationary so 

 long as they continue to menstruate. When, however, menstruation has ceased, the exhala- 

 tion of carbonic acid begins again to augment; and then again diminishes, with the advance 

 of years, as in men. Should menstruation temporarily cease at any time, the exhalation of 

 carbonic acid immediately undergoes an increase, precisely as at the final cessation of the 

 function. And during pregnancy, the exhalation increases in like manner. The following 

 table of the comparative respiration of females at different ages, will serve at the same 

 time for comparison with the preceding, so as to exhibit the general difference between the 

 two sexes, at ages nearly corresponding ; and also to indicate the peculiar modifications 

 induced by the operations of the genital system (Andral and Gavarret). 



jlfter Cessation of Catamenia. 



Carbon exhaled 



Age. 



38 years - 

 49 " 

 52 " 

 56 " 

 66 " 



per hour. 

 120-3 grains. 

 113-9 " 

 115-5 " 

 119-3 " 

 104-7 " 

 101-4 " 

 92-4 " 



Carbon exhaled 

 Age. per hour. 



10 years - - 92 '4 grains 

 13 " - 97-0 " 



During Menstrual life. 

 15^ years - - 97-0 grains. 

 26 " - - 97-0 " 

 32 " - - 95-4 " 

 45 " - - 95-4 " 76 



During Pregnancy. 82 



22 years - - 129-3 grains. 

 32 " - 126-7 " 



42 " - 120-3 " 



d. Development of the Body. The more robust the individual, cetteris paribtt?, the more 

 Carbonic Acid is exhaled ; and the variation is much more influejiced by the development 

 of the muscular system, than by the height, or weight, capacity of the chest, &c. Thus, a 

 very strong man of twenty-six years of age exhaled at the rate of 217-1 grains per hour; 

 when a man of moderate muscular power set free but 169-4 grains in the same time. An- 

 other robust man of sixty years of age exhaled at the rate of 209-4 per hour; another of 

 similar constitution, and sixty-three years of age, at the rate of 190-9 grains per hour ; and 

 an old man of 92 years, who still preserved an uncommon degree of energy, and who in 

 his younger days had boasted of extraordinary muscular powers, exhaled at the rate of 135-5 

 grains per hour. So also, a remarkably vigorous young woman of nineteen years exhaled 

 at the rate of 107-8 grains per hour ; another of twenty-two years, rather less powerful, at 

 the rate of 103-1 grains; and a strong woman of forty-four years (who had ceased to men- 

 struate) 152-4 grains. On the other hand, a slender man of forty-five years, in the enjoy- 



