6go 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 Miiller 6 rubbed mercurial oint- 
ment into clipped dogs and horses, and found mercury in the faeces and 
urine. An ointment of corrosive sublimate, sodic chloride, and fat, gave 
mercury in the faeces 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 " 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 Virchow's Archir, 1879, Bd. lxxvii. S. 157; " Verhandl. d. physiol. Gesellsch.," in 
Arch./. Physiol., Leipzig, 1880, S. 563. 
2 Arch. f. exper. Path. u. Phannakol., Leipzig, Bd. xxxi. S. 329. 
3 Virchow's Archiv, Bd. lxxix. S. 558. 4 Loc. cit. 
5 Jour n. de pharmacol., Bruxelles, 1891. 
6 Arch. f. wissenscli. u. prakt. Thierh., Berlin, Bd. xvi. S. 309 ; reference in 
Centralbl. f. Physiol., Leipzig u. Wien, 1S91, Bd. iv. S. 550. 
7 Loc. cit. 8 Loc. cit. 
9 Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 132. 
