OP THE SKIN IN GENERAL. 221 



diseases, &c. It exercises great influence over the other func- 

 tions. 



314. It is admitted that gaseous secretions and absorptions, 

 analogous to those of the lungs, and constituting a sort of cu- 

 taneous respiration, take place through the skin. Thus, Spal- 

 lanzani in the mollusca, Edwards in reptiles, and Jurine even 

 in man, have seen the skin absorb oxygen. According to 

 various natural philosophers and physiologists, gases are also 

 excreted from the skin; but objections and experiments can 

 be opposed to these assertions; the experiments of Priestly 

 may also be opposed to those of Cruikshank, of Dr. McKenzie 

 and of M. Ellis, which seem to favour the theory of a cutane- 

 ous excretion of carbone, which combines with the oxygen of 

 the atmosphere to form carbonic acid. It is at any rate cer- 

 tain, that if in man, whose epidermis is dry, and whose pul- 

 monary respiration is very great, the air exercises a vivifying 

 action upon the blood which circulates in the skin, this action 

 can in nowise supply that of the lungs. 



315. The skin excretes an oily matter,* that Cruikshank 

 succeeded in obtaining, in the form of black tears, on the sur- 

 face of a knitted woollen waistcoat that he wore night and 

 day for a month in the heat of summer. Rubbed on paper, 

 this matter acts like fat, it burns with a white flame and leaves 

 a carbonaceous residuum. It is uncertain whether this oil, 

 which has been said to be subcutaneous fat transuding through 

 the skin, is produced by the same channels as the preceding, 

 or the following. 



316. The cutaneous follicles secrete a sebaceous matter. 

 This matter is thick, not glutinous, without any fibrous ap- 

 pearance when indurated ; by suspension in water, by tritura- 

 tion, it forms a sort of emulsion, but it does not dissolve. 

 Exposed to fire, it does not melt; it burns, leaving much char- 

 coal. It chiefly contains cerumen, a proportion of oil, that 

 may be separated from it by blotting paper. This matter is 

 formed in the sebaceous follicles, whence by pressure it may 

 be forced out in the form of little worms, and whence it na- 



* Ludwig and Grutzmacher, de Humore cutem inungente. Lipsiac, 1748, 



