CUTANEOUS RESPIRA TION OF MAMMALS. 7 2 5 
removal <>f either causes death after a Longer or shorter period. The cutaneous 
respiration appears to be the more important during the winter, and the 
pulmonary during the summer. The experiments of Marcacci 1 indicate thai 
the mucous membrane of the mouth and pharynx is also respiratory in the 
frog, and Camerano 2 finds in the case of the salamanders Spelejies fuscus 
and Salamandrina perspicillata, in which the lungs are either absent or 
rudimentary, thai the bucco-pharyngeal respiration is more important than 
that carried on by the skin. 
Valentin 3 determined the absorption of oxygen and the discharge of 
carbon dioxide from pieces of skin removed from the body of the frog, and 
found that the former process was the more active. This has been confirmed 
by Waymouth Reid and Hambly, 4 who, from experiments upon the transpira- 
tion through the frog's skin, conclude that there is no evidence of any 
physiological action by virtue of which carbon dioxide is "secreted"; the 
exchange of gases is the direct result of a difference of tension on the two sides 
of the respiratory septum. 
Cutaneous respiration of mammals. — In man and other mammals 
the cutaneous respiration is so small that it has been denied by some 
observers, 5 and explained away by others, as arising from the decom- 
position of filth and cutaneous secretions. 6 Although Hippocrates and 
Galen believed in the absorption of air by the skin, no experiments 
appear to have been made until the year 1777, when Milly observed, 
during a warm bath, a number of small bubbles attached to the surface 
of his body ; some of these bubbles were collected, and on analysis were 
found by Lavoisier 7 to be carbon dioxide. Objection was raised to this 
experiment, on the ground that carbon dioxide present in the water 
might attach itself to the body, as it does to other solid substances. 
Cruikshank, 8 however, found that air, in which a previously washed 
hand or foot had been confined for one hour, caused a marked turbidity 
with lime water. These experiments were extended by Abernethy, 9 
who showed that in ordinary air oxygen was absorbed and carbon 
dioxide was given off as readily as in pure oxygen, whereas in carbon 
dioxide gas nitrogen was discharged and carbon dioxide absorbed by the 
skin of the hand. 
In Lavoisier and Seguin's 10 experiments a man was enclosed in an 
air-tight rubber bag, while he breathed through two tubes connected 
with the mouth and nose ; this method was improved by Scharling, 11 
who prevented the excessive accumulation of moisture by ventilating 
the chamber in which the subject of the experiment w r as confined. 
The results of the above and later observers are given in the following 
table : — 
1 Arch. ital. de biol., Turin, vol. xxi. p. 1. 
- Ibid., vol. xxi. p. 387. 
3 Arch.f. physiol. Heilk., Stuttgart, 1855, S. 474. 
4 Journ. Physiol., Cambridge and London, 1895, vol. xviii. ]>. 411. 
5 Priestley, "On Air," vol. ii. pp. 193, 194; Klapp and Gordon, "Ellis's Inquiry" 
Edinburgh, 1807, pp. 189, 354. 
6 Hoppe-Seyler, ••'Physiol. Chem.," Berlin, 1879, Bd. iii. S. 580. 
''Hist. Acad. rot/, d. sc, Paris, 1777, pp. 221, 360. 
8 "Experiments on the Insensible Perspiration of the Human Body, showing its 
affinity to Respiration," 2nd edition, London, 1795, pp. 81, 82. 
9 "Surgical and Physiological Essays," London, 1793, pt. 2, p. 107. 
10 "(Euvres de Lavoisier," Paris, 1862, tome ii. p. 708 ; Ann. de chim. et phys., 
Paris, 1S14, tome xc. p. 8. 
11 Journ. f. prakt. Chem., Leipzig, 1845, Bd. xxxvi. S. 454 : Ann. de chim. et phys., 
Paris, 1843, Ser. 3, tome viii. p. 480. 
