ANIMAL FLUIDS INTO THE BLOOD. 59 



to come in direct contact with the liquid on the 

 outside of the pores, it follows, that, when this 

 second liquid moves past the pores with a certain 

 velocity, the absorbed liquid must follow it during 

 the mixture, and there must take place a rapid analogous 



to suction. 



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 * occ v rs 



J in the am- 



of this kind in the most perfect form. The blood- mai body. 



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 Absorption 

 system of blood-vessels, and all the animal fluids, liquids of 



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. 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 part of the gland. The 



