PROPERTIES OF ANIMAL BODIES. 101 



with great facility. The epidermis or cuticle of the skin 

 permits fluids to pass with difficulty. That water is taken 

 up in considerable quantity, however, is proved by the fact, 

 which has often been proved by experiment, that a man in- 

 creases in weight by remaining for a considerable time in a 

 warm bath. 



30. The following experiments prove the nature of this 

 process. |lf we fill the intestine of a chicken with milk, and 

 place it in water, we shall see the milk pass through its 

 coats into the water, and the water will pass through in an 

 opposite direction to supply its place. In the same manner, 

 if a bladder be filled with hydrogen gas, and suspended in 

 the air, in a short time it will be found to be mixed with 

 atmospheric air, which has passed through its coats. The 

 result of all the experiments on this subject seems to show, 

 that when any cavity containing a fluid is immersed in 

 another fluid less dense than the former, there is a tendency 

 in tfye membrane to expel the denser, and absorb the thinner 



31. Many of the animal tissues are indebted for their 

 physical properties to the water they imbibe. If they are 

 deprived of this water, they are unable to perform their 

 proper office and function, until they are again supplied with 

 it. Hence one important reason why the system craves 

 water, and why the want of it produces such distressing 

 effects. 



32. (By the functions of man, we understand the opera- 

 tion of the various organs^ in other words, his vital actions. 

 fyife is made up of a constant series of these actions, from 

 the period of birth to the moment of dissolution. Physiol- 

 ogists have attempted to define life ; but the best definition we 

 can give is, that^t is an assemblage of actions^ Indeed, the 

 essential nature of life is an impenetrable mystery, and not 

 a proper subject for philosophical inquiry. As the fluids 

 are as mucK endowed with life as the solids, it cannot be 

 said that life is the "effect of organization ;" besides, a 



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