ABSORPTION B Y THE SKIN IN MAN. 685 



ABSORPTION BY THE SKIN. 



Man. To decide the case for or against the possibility of absorption 

 by the human skin, would appear a simple problem, yet a literature 

 reaching back over a century indicates that the production of un- 

 impeachable testimony on either side has proved a matter of no little 

 difficulty. 



A fluid in contact with the skin is separated from the blood vessels 

 by layers of epidermic cells with intercellular spaces, but since the 

 superficial cells (except in the palm of the hand and sole of the foot) 

 are greasy with sebum, one of the first conditions for absorption is that 

 the fluid shall be able to wet the surface, so that imbibition by the cells, 

 or entrance of the fluid into the capillary spaces between them, may 

 take place. Though lanoline, the natural fat of the skin, takes up 

 water, such action only occurs slowly, and unless the skin is soaked 

 long in warm water, it is a familiar observation that it does not easily 

 become sodden, except in the case of the palms and soles. It is there- 

 fore not to be expected that water or watery solutions will be capable 

 of absorption by the skin of man, and the experimental evidence is 

 distinctly against such an assumption. 



The method of some of the older observers, of attempting to decide 

 the question of absorption of water by immersing a man in a bath after 

 weighing, and weighing again after a prolonged sojourn therein, we may 

 dismiss by a bald statement of obvious sources of error. 



(a) There is no guarantee that the normal loss of weight of the body 

 per unit time, through lungs and skin, is the same during the bath as 

 estimated during preceding hours. (The experiments showed, in different 

 instances, gains, losses, and absence of change of weight.) 1 



Further, mere soakage of the epidermis of palms and soles may 

 mask an actual loss of weight in the bath. 2 



(b) It is impossible to be certain that the epidermis of the whole 

 body is devoid of fissures through which water might reach the deeper 

 parts. 



(c) It is difficult to totally exclude absorption by immersed mucous 

 surfaces. 



(d) A balance sensitive enough to indicate a difference of a few 

 grammes on a weight of many kilos., is difficult to construct. 



(e) A considerable loss of surface epidermis occurs in " drying " the 

 body with a towel. 



An improvement upon the method of total immersion is that of 

 immersion of a part of the body, but the vessel, instead of being 

 weighed before and after immersion of the part of the body, as in the 

 experiments of Vierordt and Eichberg, 3 is be'tter graduated as in the 

 experiments of Falck, 4 or provided with a capillary pipette, by means of 

 which absorption can be determined by fall of level of fluid, 5 because, 

 by the gravimetric method, the error from mere soakage of epidermis 

 becomes far larger than in the volumetric method, though here also a 

 slight diminution in volume accompanies imbibition by the palm or sole, 



1 Jainin et de Laures, Compt. rend. Acad. d. sc., Paris, 1872, tome Ixxv. p. 60. 



2 Poulet, ibid., 1856, tome xlii. p. 435. 



3 Arch. f. physiol. Heilk., Stuttgart, 1856. 4 Ibid., 1852. 



5 Madden, "An Experimental Inquiry into the Physiology of Cutaneous Absorption," 

 Edinburgh, 1838; Fleischer, Inaug. Diss., Erlangen, 1877. 



