RESPIRATION BY THE SKIN. 
723 
Sex. 
Age. 
Weight. 
Output of 
Carbon Dioxide in 
Twenty-four Hours. 
Output of 
Carbon Dioxide 
per Kilo, and Hour. 
Male 
35 years 
Kilo. 
65-5 
Gnus. 
804-72 
Grins. 
0-51 2 
) j 
28 ,, 
82 
878-95 
0-497 
„ . . 
16 ,, 
5775 
822-69 
0-594 
Female . 
19 ,, 
55-75 
608-22 
0-455 
Male 
n >, 
22 
488-14 
0-925 
Female . 
10 ,, 
23 
459-87 
0-833 
A series of experiments by Pembrey l has shown that the effect of 
age upon the respiratory exchange must be considered in relation to the 
temperature of the external air and the stage of development in which 
the animal is at birth. Animals born in a condition of advanced 
development, like that of guinea-pigs and chickens, have a respiratory 
exchange which is relatively two or three times greater than that of 
the adult. Animals born in a helpless state, like that of mice and 
pigeons, have at the ordinary temperature of the air a metabolism 
relatively smaller than that of the adult ; but with a rise in the 
external temperature towards the temperature of the body the re- 
spiratory exchange increases towards the value in the adult. These 
differences, which are intimately connected with the temperature of 
the animal, are discussed more fully in other parts 2 of this work. 
Respiration by the Skin and Alimentary Canal. 
Cutaneous respiration of amphibia. — In many of the lower animals 
the exchange of gases between the skin and the surrounding air or water is 
considerable, and in some of the amphibia is equal to, or even greater than, that 
effected by the lungs. As early as the end of the last century, Spallanzani 3 
showed that many amphibia could readily take up oxygen and discharge 
carbon dioxide after their lungs had been removed, and that in this condition 
they lived longer than animals of the same species whose skin had been 
covered with varnish. These observations were extended by Edwards, 4 
who found that frogs deprived of their lungs would live a long time, provided 
that the external temperature was low. This cutaneous respiration took place 
as readily in flowing water as in air, for normal frogs could lie kept alive 
although never allowed to come to the surface, provided that the temperature 
of the water did not exceed 12°; the cutaneous respiration was sufficient for 
the small amount of metabolism which occurred at low temperatures. Regnault 
and Reiset 5 found, by direct experiment, that frogs absorbed as much oxygen 
and discharged as much carbon dioxide after, as before, removal of their 
lungs. The following figures give their results : — 
1 Jouni. Physiol., Cambridge and London, 1895, vol. xviii. p. 363. 
2 See " Animal Heat," this Text-book, vol. i. 
:; ' : Memoires sur la respiration," trad, par Senebier, Geneve, 1803, pp. 72, 114. 
4 "De l'influence des agens physiques sur la vie," Paris, 1S24, pp. 12, 41-62. 
5 Ann. de chim. etphys., Paris, 1849, Ser. 3, tome xxvi. p. 506. 
