ABSORPTION BY THE SKIN. 241 



that for combustible material. I have now to present the skin under the 

 same aspect. It is not a mere analogy that exists between the action of 

 these organs ; the occurrence of urea and of the salt substances, the names 

 of which have been specified in both secretions, is a fact of the utmost sig- 

 nificance. I believe that the sudoriparous glands are the counterparts 

 of the Malpighian bodies, and the sebaceous glands, in their function, are 

 the counterparts of the uriniferous tubes. Indeed, this double action is 

 also distinguished in the case of the mucous membranes, which possess 

 one instrumental arrangement for the transit of saline solutions, and an- 

 other for that of fats. And since the skin, the mucous membrane, and 

 the great glands connected with it, are all to be regarded as developments 

 of one original tissue, we should expect to discover, even in their concen- 

 tration or specialization of function, the traces of their original and com- 

 mon property. Development takes place from the general to the special ; 

 and hence, in parts which have arisen from the same primordial structure, 

 though they may be charged with the accomplishment of functions which, 

 in appearance, differ essentially, there may be, both in their action and 

 in their construction, the traces of their original identity. It is in this 

 manner that the kidneys, and skin, and mucous membrane, possess the 

 property of acting vicariously for one another. The kidney can dis- 

 charge water for the skin, or the skin urea for the kidney. The com- 

 bustible matter, known as extractive in the urine, can be set free under 

 diminished renal action by the sebaceous glands, and the saline solutions, 

 eliminated by the convoluted tubing of the tufts of Malpighi, can be set 

 free by the convoluted tubing of the sudoriparous glands. In connection 

 with the views I am here impressing, I would recall the structural and 

 functional analogy there is between the transuding mechanism of the 

 kidney and the transuding mechanism of the skin. Both are arrange- 

 ments of thin convoluted tubes, and the same may be remarked as re- 

 gards the elimination of combustible material, which is probably accom- 

 plished by cell action in the uriniferous tubes, and again by cell action 

 in the sebaceous glands. 



Besides exercising the functions of exhalation and perspiration, nu- 

 merous facts demonstrate that the skin exerts an absorbent Absorption by 

 action. The endermic application of remedial agents estab- of g 

 lishes this in a satisfactory manner. That water can find liquids, 

 access in this way is shown by the assuaging of the thirst which may 

 occur on taking a bath ; nor is the amount insignificant, since it may 

 give rise to a considerable increase of weight. Thus lizards, which have 

 been kept in a dry atmosphere, and thereby suffered a diminution, recov- 

 er their original weight after immersion in water ; nor is it necessary 

 that the whole .skin should be brought into contact with that liquid ; 

 the same result is obtained if merely the tail and hinder parts are im- 



Q 



