ABSOKPTTON FEOM THE SKIN". 451 



into the circulation through the skin, the lining membrane 

 of the air-passages, the reservoirs, dncts, and parenchyma of 

 glands, the serous and other closed cavities, the areolar tis- 

 sues, the conjunctiva, the muscular tissue, and, in fact, all 

 parts which are supplied with blood-vessels; but here the 

 absorption of foreign matters is an occasional or an acci- 

 dental circumstance, and is not connected with the general 

 process of nutrition. It is now well known that all parts 

 of the body, except the epidermis and its appendages, the 

 epithelium, and some other structures which are regularly 

 desquamated, are constantly undergoing change, and the 

 effete matters which result from their decay are taken up 

 by what is called interstitial absorption, and carried by the 

 blood to the proper organs, to be excreted. It would seem 

 probable that the vessels of these parts would also be capable 

 of taking up soluble foreign substances when presented to 

 them ; and this is, indeed, the fact with regard to all parts in 

 which the nutritive processes are even moderately active, or 

 where the structures covering the vascular parts are per- 

 meable. 



Absorption from the Skin. It is now generally admitted 

 that absorption can take place from the general surface, 

 though at one time this was a question much discussed by 

 physiologists and practical physicians. The proofs, however, 

 of the entrance of certain medicinal preparations from the 

 surface of the body are now entirely conclusive ; and the con- 

 stitutional effects of medicines administered in this way are 

 frequently as marked as when they are taken into the ali- 

 mentary canal. But the question which is of most interest 

 to us as physiologists concerns the normal functions of the 

 skin as an absorbing surface. 



Looking at this subject purely from a physiological point 

 of view, absorption from the skin, under ordinary conditions, 

 must be exceedingly slight, if, indeed, it take place at all. 

 There are a few observations by the older physiologists 



