CUTANEOUS RESPIRA TION OF MAMMALS. 7 2 5 



removal of 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 l indicate that 

 the mucous membrane of the mouth and pharynx is also respiratory in the 

 frog, and Camerano 2 finds in the case of the salamanders Spelepes fuscus 

 and Salamandrina perspicillata, in which the lungs are either absent or 

 rudimentary, that 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 Way mouth 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-tigbt 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 was 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. 



2 Ibid., vol. xxi. p. 387. 



3 Arch.f. physwL ffeilk., Stuttgart, 1855, S. 474. 



4 Journ. PhysioL, Cambridge and London, 1895, vol. xviii. p. 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. Hi. S. 580. 

 7 Hist. Acad. roy. 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, 1814, tome xc. p. 8. 



11 Journ. f. prakt. Chem., Leipzig, 1845, Bd. xxxvi. S. 454 ; Ann, de cjrim. et phys., 

 Paris, 1843, Se>. 3, tome viii. p. 480. 



