LOWER MAMMALS. 689 



cases as analogous. The skin of the mammals usually employed for such 

 experiments is thinner than that of man, less horny, more vascular on 

 account of the hair, and in some cases (rabbit) possessed of hair follicles 

 with wide mouths. The presence of hair is a source of trouble in experi- 

 ment, for, if not shaved, excoriations may be passed over, while, on the 

 other hand, the process of shaving is apt to be accompanied by slight 

 injuries to the surface. 



As with man, so here there is little positive evidence of absorption of 

 watery solutions, and one is inclined to attribute the results of those 

 observers who maintain that watery solutions are absorbed, to injuries 

 produced in shaving, or clipping, or accidental introduction by mouth or 

 lungs. 



Forlanini 1 maintained that rabbits could be poisoned by painting 

 aqueous solutions of strychnia, acidulated with acetic acid, on the skin, 

 but v. Wittich 2 could not get the effect on white rats, nor Fubini and 

 Pierini 3 with guinea-pigs, while Winternitz 4 obtained both positive and 

 negative results with live rabbits. Fubini and Pierini allowed the tails 

 of rats to soak in strychnia and potassium cyanide solutions (for forty 

 minutes in the former case and two hours in the latter) without effect. 

 Traube-Mengarini 5 painted the skin of dogs daily for two months 

 with aqueous solution of potassium ferrocyanide, killed the animals, and 

 treated skin sections with ferric chloride. The blue was only found 

 between the surface cells, not reaching deeper than the stratum granu- 

 losum. Acidified borax-carmine solution, applied daily for seventy days, 

 gave a like result. Fleischer 6 got iodine through the belly skin of a 

 rabbit (into a watch-glass of water introduced under the skin) in two 

 hours from a cylinder full of the tincture, but admits that the structure 

 of the skin was altered. 



With ether and chloroform solutions, absorption is more marked 

 in the thin skin of the rabbit, guinea-pig, and rat, than in that of man. 



Waller 7 immersed the leg of a guinea-pig in a mixture of chloroform 

 and tincture of aconite, and was able to poison the animal, an effect not 

 produced by the tincture alone. White rats with the foot in a chloro- 

 form solution of atropine, exhibited a dilated pupil in two or three 

 minutes ; with the tail (thicker skin) immersed, not till half an hour 

 had elapsed. Strychnia in the same way he found was absorbed from 

 solutions in chloroform, but not from those in alcohol. 



Winternitz 8 also found that rabbits absorb strychnia solution in 

 chloroform, and points out that this is not merely an effect of " stimu- 

 lation," because a previous treatment of the skin with mustard or 

 ammonia does not hasten the intoxication. 



Winternitz has also pointed out that cleansing the skin of rabbits 

 with ether or chloroform allows absorption of aqueous strychnia solution 

 to take place, and, microscopically, it is found that silver nitrate solution 

 penetrates more deeply if the skin is so treated. Alcoholic washing of 

 the skin also tends to make subsequent absorption of aqueous solution 

 possible, but to a far slighter degree than in the case of chloroform and 

 ether. 



1 Ann. univ. di med. e chir., Milano, 1868, vol. ccv. p. 473. 



2 Loc. cit. 3 LOG. cit. 4 Loc. cit. 



5 Arch. f. PhysioL, Leipzig, 1892, Supp., S. 1; Arch. ital. de UoL, Turin, 1891, 

 vol. xvi. p. 159. 



6 Loc. cit. 7 Proc. Roy. Soc. London, 1860, vol. x. p. 122. 8 Loc. cit. 



VOL. i. 44 



