N 



184 ANATOMY AND PHYSIOLOGY. 



the body (such as the poison of fever*). And it is important to 

 bear this last circumstance in mind ; since it enables us to understand 

 how, if time be given, the system frees itself from such noxious 

 substances ; and points out the duty of the medical attendant to be 

 rather that of supporting the powers of the body by judiciously 

 devised means, and of aiding the elimination of the morbid matter 

 through the lungs and skin by a copious supply of pure air, than of 

 interfering more actively to promote that which Nature is already 

 effecting in the most advantageous manner. 



[Suitable views of the liver will be found in Lizars' Colored Plates, page 86, and of 

 the kidneys, at page 88.] 



CHAPTER XI. 



EXHALATION AND ABSORPTION. 



BY exhalation is meant the escape of some portion of the- con- 

 tents of the blood-vessels (generally little altered), probably through 

 pores in their sides. When a fluid, colored with vermilion, is in- 

 jected into the blood-vessels of a dead animal, the fluid portion will 

 pass out of them, and is said to be exhaled, while the vermilion is 

 retained ; or when a solution of phosphorus is thrown into the veins 

 of a living animal, in a few seconds fumes of phosphorous acid are 

 given off from its lungs. By absorption is meant the removal of 

 the soft or hard parts of the body, or of substances placed in con- 

 tact with these parts. When a fat person becomes lean, or the 

 fluid in a dropsical person's belly has disappeared, the fat and the 

 fluid are said to have been absorbed. 



The three most important exhaling and absorbing surfaces, are 

 the intestinal canal, the lungs, and the skin ; but these processes 

 are active also in the chest, belly, and other cavities. We have 

 already explained the structure of the intestinal canal and lungs, 

 and the skin will be treated of at the close of this chapter, so that 

 it will be necessary at present only to say that the skin has a thin 



* There is strong reason to believe that, in many instances, a small amount of poi- 

 sonous matter introduced from without, in the form of a contagion or miasm, may 

 lead, by a process resembling fermentation, to the production of a large quantity of simi- 

 lar noxious substances in the animal fluids. 



