129 



on the surface of the glands, Sec. The complete removal of the epider- 

 mis, favours absorption from all parts of the skin which it covered. 

 Hence the least scratch on the fingers of an accoucheur touching women 

 infected with the venereal virus, exposes him to this peculiar infection, 

 which, in such cases, is the more to be dreaded, from the admission of 

 the virus by an unusual course. The innoculation of variolous and vac- 

 cine matter, equally furnishes proofs of the obstacle which the epidermis 

 presents to cutaneous absorption, and of the facility with which that func- 

 tion takes place, from surfaces denuded of that covering. Absorption 

 goes on, likewise, with great activity, from the surfaces of internal parts, 

 but it no where is so considerable, as in the intestinal canal, and it would 

 perhaps be the most favourable part for introducing medicinal substances 

 into the animal economy, if when swallowed, they did not undergo changes, 

 by mixing with the gastric juices, or with the intestinal fluids and faecal 

 substances, when injected by the ?ectum. From the evacuation by urine 

 of clysters of warm water, soon after they have been administered, it is to 

 be presumed, that the great intestines absorb, almost as powerfully as the 

 rest of the digestive canal. A pint of warm water injected into the abdo- 

 men of a large dog or sheep, is often absorbed in less than an hour, and 

 the effusions which take place in those cavities, would possibly not re- 

 quire an operation to let them out, if such fluids were not subject to coa- 

 gulation, and if the absorbing surfaces were not diseased. 



Besides absorption from surfaces, there exists, as we have already stated, 

 another which takes place in the living solid, and in the internal substance 

 of the organs. It is by this kind of absorption, that the nutritive decom- 

 position is effected ; by means of it, the living matter is incessantly reno- 

 vated. Its vitiated action accounts for the spontaneous formation of 

 ulcers, the disappearing of the thymus, the atrophy of parts in which nu- 

 trition is carried on, in a sluggish manner ; the resolution of certain 

 tumours, and many other phenomena, are dependent on the same cause. 

 I do not think, however, that it is possible to admit the explanation of the 

 sensation of hunger, adopted by Professor Dumas, who believes that it 

 depends on the action of the absorbing orifices directed against the or- 

 ganized substance of the stomach, in the absence of aliment on which to 

 act*. The sensation of hunger is felt only in the stomach, although its 

 effects extend to all parts of the body: it begins in a circumscribed spot, 

 its seat is limited, yet absorption takes place every where, so that if the 

 hypothesis in question had any foundation, the sensation of hunger ought 

 to be felt at the heel, as well as at the pit of the stomachf. 



* Both hunger and thirst seem to be sensations, excited by the stomach's sympathis- 

 ing with the general exhaustion of the system, and are the means employed by nature 

 to admonish us of the necessity of repairing the wastes which it sustains from abstinence. 

 An office so imporsant to our well being, and even existence, is not left to reason, 

 which might often err, but is put under the care of an instinct, far more certain in its 

 operation. Besides these two sensations, the stomach has others equally specific : as 

 satiety, longing, loathing, sickness, &c. &c. Chapman. 



f It does not fall to the lot of every one, to err like M. Dumas, whose talents and in- 

 genuity I have much pleasure in acknowledging. He imagines rickets to consist, in 

 a deficient influence of the nervous system on the bones; which would constitute a 

 kind of paralysis. Anatomy shows the presence of no nerves in the tissue of thebones> 

 and veins and arteries are alone seen to enter the foramina, and no nerves appear 

 to be transmitted through them. The functions of the bones made it unnecessary that 



