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A very simple mode of demonstrating the existence of cutaneous 

 absorption is by immersing the leg of a young guinea pig, not more 

 than half-grown, into a mixture of equal parts of chloroform and 

 tincture of aconite. After 15 minutes' immersion, the part will be 

 found insensible at the surface and extremities, and, after a short 

 time, symptons of poisoning by aconite will supervene, viz. : nausea, 

 efforts at vomiting, sometimes vomiting of bile, coldness of the 

 surface and extremities, circulation very weak, laborious respiration, 

 slight convulsive symptoms, and death. 



The influence of age, or of thickening of the cuticle, is easily seen 

 in the same way ; for, if instead of a young animal we take an adult 

 one, we obtain no poisoning, but merely local insensibility and slight 

 disturbance of respiration, &c. 



Another not less instructive experiment consists in replacing the 

 mixture of chloroform and tincture of aconite by simple tincture of 

 aconite. In this case, the limb may be indefinitely immersed without 

 our obtaining either local insensibility, or death, or indeed any 

 symptom whatever of the presence of aconite in the system. 



A fourth experiment, which consists in dividing the sciatic nerve, 

 shows the influence of innervation on the function of absorption ; for, 

 if performed on an adult animal, and consequently one incapable of 

 absorbing aconite in quantity sufficient to cause death, the powers of 

 absorption will be generally found so much augmented that the 

 animal will be poisoned by immersion of the limb in simple tincture 

 of aconite. 



In this experiment I attribute the acceleration in the cutaneous 

 absorption to the paralysis of the blood vessels, as in my experiments 

 on the sympathetic nerve, where I showed that in blood vessels the 

 passage of the blood is completely regulated by nerves springing 

 from the spinal cord. When the vascular nerves are paralysed, the 

 artery becomes greatly distended, and the blood flows faster within it. 

 The foot after the section of the sciatic is, on this account, more hot 

 and red ; and for the same reasons it is easy to account for the more 

 rapid absorption of medicinal agents. 



A fifth experiment consists in placing a ligature on the limb, in 

 order to impede the powers of absorption of the animal. Although 

 the ligature does produce this result, I was rather surprised to find 

 how much less efficient it was than is generally represented ; for, 



