294 PHYSIOLOGY. 



hol is an exception, as it frequently, if not always, passes 

 into the blood unchanged. 



8. Various medicinal substances are absorbed, and enter 

 the circulation, nearly or wholly unchanged. ^Colouring 

 matter, such as madder, is taken up and carried into the 

 blood, and even tinges the bones. ^ Odoriferous particles, 

 such as of garlic, camphor, asparagus, &c., are also readily 

 absorbed, and in this way the blood derives its saline proper- 

 ties. It is pretty well established, that articles not of an 

 alimentary nature, which are absorbed, are chiefly taken up 

 by the veins, while the lacteals absorb chyle more readily 

 than any other substances. 



9. Absorption takes place from the external surface or 

 skin. This is proved by many facts. Thirst may be 

 quenched by applying moist cloths to the skin, or by bath- 

 ing. The body increases in weight by the use of the bath ; 

 and it has been found that the hand, immersed to the wrist 

 in warm water, will absorb from 90 to 100 grains of fluid 

 in the space of one hour. The saliva has become bitter by 

 the absorption of sea water ; and it is stated that patients 

 have been supported by baths of milk or broth. 



10. Medicinal substances are often absorbed by the skin. 

 Mercury, Spanish fly, morphine, and many other articles are 

 frequently introduced into the system through the skin. 

 Metallic quicksilver has been found in the bones of persons 

 who had been subjected to mecurial frictions ; and it has 

 also been obtained by distilling the blood of rabbits, dogs, 

 and cats, which had been rubbed with this mineral. Gases 

 are also absorbed by the skin. 



11. As every part of the body is subject to constant re. 

 novation and change, absorption must be (continually going 

 on among the particles and substance of which each organ 

 is composed.^ This is called interstitial absorption. It is 

 this which counterbalances the action of the nutrient ves- 

 sels, and preserves tjie form and size of every part of the 

 body, p hen it is too active, the body emaciatesjfc *vhen it 



