690 SECRETION AND ABSORPTION BY THE SKIN. 



Experiments upon the absorption of oils and unguents by the 

 skin of animals seem to have given conflicting results in the hands 

 of different observers. Lassar 1 anointed rabbits with oil for days in 

 succession, and maintains that the organs became loaded with oil. V. 

 Sobieranski 2 asserts the same for vaseline rubbed into the skin of dogs 

 and rabbits, and states that the substance is found especially in the 

 muscles. Fleischer 3 denies the effect, as also does Winternitz, 4 though 

 the latter observer was able to kill a rabbit by inunction of strychnia 

 (2 per cent.) in oil. Adam and Schoumaker 5 got negative results 

 from the inunction of an ointment of strychnia and vaseline into the 

 skin of the necks of dogs. Mercury, however, is absorbed by dogs and 

 horses from mercurial ointment. Thus Mtiller 6 rubbed mercurial oint- 

 ment into clipped dogs and horses, arTd found mercury in the freces and 

 urine. An ointment of corrosive sublimate, sodic chloride, and fat, gave 

 mercury in the fseces and urine ; lead was passed after rubbing in an 

 ointment of a lead salt, and application of a potassic iodide ointment 

 gave iodine in the saliva. Aqueous solutions of sublimate were without 

 effect when applied to the skin of these animals. 



Cataphoric transfer of solutions through the skins of lower mammals 

 can be induced more easily than in the case of man. Munk T was able to 

 poison rabbits with strychnia in aqueous solution, and Kahn 8 obtained 

 the pharmacological effects of physostigmine and strychnia on rabbits, 

 and of apomorphine on dogs, by passing a current of 3'5 milliamperes 

 through '2 per cent, solutions in the positive electrode, and in all cases 

 proved that applications of the solutions without concomitant passage 

 of current was without effect. 



Frog. In the case of the frog the conditions for absorption of 

 watery solutions by the skin are far more favourable than in that of 

 mammals, for the surface is kept constantly moist by the secretion of 

 the skin glands, and no greasy matter is present, so that it is a matter 

 of common laboratory experience that poisonous solutions applied to 

 the skin of the animal rapidly produce their specific effects. 



Blood vessels are abundant in the skin, especially in that of the 

 back, and substances must diffuse with ease through or between the 

 moist epidermic cells into the underlying vessels. It would, however, 

 appear probable that, in addition to simple diffusion, the physiological 

 condition of the lower epidermic cells affects the passage of substances 

 through the skin. 



Eeid 9 found that the direction of easier osmotic transfer of fluid 

 through freshly removed frog's skin is (provided the fluids used are 

 not deleterious) from without inwards, i.e. the reverse of the direction 

 of easier filtration through the dead skin ; but that, as its vitality 

 declines, the skin becomes less and less permeable from without 

 inwards, and finally is more permeable in the reverse direction. The 

 duration of the first period, during which the skin is more permeable 



1 Virchows Archiv, 1879, Bd. Ixxvii. S. 157 ; " Verliandl. d. physiol. Gesellsch.," in 

 Arch. f. Physiol., Leipzig, 1880, S. 563. 



2 Arch.f. cxper. Path. u. Pharmakol., Leipzig, Bd. xxxi. S. 329. 



3 Virchow's Archiv, Bd. Ixxix. S. 558. 4 Loc. cit. 



5 Jour n. depharmacol., Bruxelles, 1891. 



6 Arch. f. wissensch. u. prakt. T/iierh., Berlin, Bd. xvi. S. 309 ; reference in 

 Centmlbl.f. Physiol., Leipzig u. Wien, 1SP1, Bd. iv. S. 550. 



7 Loc. cit. 8 Loc. cit. 

 9 Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 132. 



