LECT. IV. LAWS OF ABSORPTION. 89 



culty this function ; but, by removing the epidermis, we 

 render the skin more capable of absorption. 



11 3dly. Absorption varies according to the quantity of 

 liquid which exists in the organism, and is in the inverse 

 ratio of the plethoric state of the animal." 



If you remember the phenomenon of imbibition, you will 

 easily comprehend this law of the function. A mass of 

 sand, if saturated with liquid, cannot further imbibe ; and, 

 on the other hand, imbibes so much the more rapidly, as it 

 is further removed from the point of saturation. 



Dutrochet exposed a plant to the air until it had lost by 

 evaporation 0.15 of its weight ; and afterwards, by plunging 

 it into water, he found that in each of the first four hours 

 of immersion, it absorbed ls r .05 (20 grains,) and lost r .40 

 (8 grains ;) subsequently it absorbed only r .45 (9 grains,) 

 and lost as much by exhalation. Edwards found that frogs 

 absorbed water the more rapidly in proportion as they had 

 lost more of their weight by transpiration. 



Magendie mentions that a dog, from which a large quan- 

 tity of blood had been drawn, died rapidly from poisoning 

 by strychnia; whilst another animal, into whose veins a 

 large quantity of water had been injected, did not present 

 symptoms of poisoning. 



" 4thly. Within certain limits, absorption is in proportion 

 to the temperature of the absorbing body, and of the body 

 absorbed." 



Every one knows that warm drinks operate more quickly 

 than cold ones. So also with imbibition, which, as we have 

 seen, varies greatly according to the temperature. I have 

 $aid, that this variation can only be effected within certain 

 limits, for beyond these the structure of the organized body 

 will be altered. 



" 5thly. According to Fodera, the electric current favours 

 absorption." 



