PO MOTION OF THE JUICES OF THE ANIMAL BODY. 



to be difficultly permeable for one liquid, while the other is easily taken up into its 

 pores, and if we reflect, that this second liquid, on entering into the pores of the 

 bladder, in virtue of the attraction of their walls for it, acquires a certain velocity 

 which permits it to pass beyond the extremitiss of the canal or the pores, so as to 

 entirely fill the pores, and to come in direct contact with the liquid on the outside 

 of the pores, it follows, that, when this second liquid moves past the poses with a 

 certain velocity, the absorbed liquid must follow it during the mixture, and there 

 must take place a rapid transference of the second liquid to the first, a true suction 

 as if by a pump. 



The animal body is an example of an apparatus of this kind in the most perfect 

 form.* The blood vessels contain a liquid, for which their walls are, in the 

 normal state, far less permeable than for all the other fluids of the body. The 

 blood moves in them with a certain velocity, and is kept at all times in a nearly 

 uniform state of concentration by a special apparatus, namely, the urinary 

 organs. 



The whole intestinal canal is surrounded with this system of blood vessels, and 

 all the animal fluids, in so far as they are capable of being taken up by the parietes 

 of the intestinal canal, and of the blood vessels situated around it, are rapidly 

 mixed with the blood.t The volume of the blood increases, if no compensation 

 is effected by means of the kidneys : and the intestine is emptied of the liquids 

 contained in it. The intestinal glands, through which this transference is effected, 

 and each of which represents a similar apparatus of suction, contain, within them, 

 two systems of canals, blood vessels and lacteals; the blood vessels are placed 

 next to the external absorbent surface, the lacteals chiefly occupy the central pait 

 of the gland. The liquids circulating in these two systems have very unequal 

 velocities, and as the blood moves much faster in the blood vessels, we perceive how 

 it happens, that the fluids of the intestine are chiefly (in quantity and in velocity) 

 taken up into the circulation. 



The difference in the absorbent power of the parietes of the intestinal canal for 

 liquids which contain unequal amounts of dissolved matters, is easily observed in 

 the effects produced on the organism by water and saline solution s.J 



If we take while fasting, every ten minutes, a glass of ordinary spring water 

 the saline contents of which are much less than those of the blood, there occurs, 

 after the second glass (each glass containing 4 ounces,) an evacuation of colored 

 urine, the weight of which is very nearly equal to that of the first glass ; and after 

 taking, in this way, 20 such glasses of water, we have had 19 evacuations of urine, 

 the last of which is colorless, and contains hardly more saline matter than the 

 spring water. 



If we make the same experiment with a water, containing as much saline matter 

 as the blood ( to 1 per cent, of sea salt,) there is no unusual discharge of urine, 

 and it is difficult to drink more than three glasses of such water. A sense of 

 repletion, pressure, and weight of the stomach point out, that water as strongly 

 charged with saline matter as the blood requires a longer time for its absorption 

 into the blood vessels. 



Finally, if we drink a solution containing rather more salt than the blood, a 

 more or less decided catharsis ensues. 



The action of solution of salt is of three kinds, according to the proportion of 

 salt. Spring water is taken up into the blood vessels with great rapidity ; while 

 these vessels exhibit a very small power of absorption for water containing the 

 same proportion of salt as the blood does ; and a still more strongly saline solu- 

 tion passes out of the body not through the kidneys, but through the intestinal 

 canal. 



Saline solutions and water, given in the form of enemata, exhibit similar 

 phenomena in the rectum. || Pure water is very rapidly absorbed, and excreted 



* This occurs in the animal body. 



t Absorption of the liquids of the intestines into the blood, 

 j Effects produced by drinking water and saline solutions. 



* Solution containing more salt than the blood. 

 o Enemata of water and saline solutions. 



