90 EXHALATION. L.ECT IV. 



If we admit the experiments of this physiologist, it is not 

 easy to explain the fact now stated, because, when we em- 

 ploy the electric current in imbibition, we do not observe 

 this influence. The fact mentioned by Porret alone,* and 

 which consists in the transit of water from the positive to 

 the negative pole, may in some way explain the results ob- 

 tained by Fodera. 



" 6thly. Lastly, absorption varies according to the ra- 

 pidity with which the liquid moves in the absorbing ves- 

 sel." 



It is unnecessary to state how this rapidity serves to 

 carry more or less quickly, and to a given distance, the 

 absorbed body. It is equally easy to understand, that as 

 the molecules of the liquid contained in the vessel are the 

 more frequently renewed, so the actions of affinity, which 

 tend to promote the absorption of the body into the inte- 

 rior of the vessel, become more energetic. This, proba- 

 bly, is the reason why absorption is slower by the chylife- 

 rous and lymphatic vessels than by the veins. Hence, 

 many coloured substances, alcoholic liquids, and saline 

 solutions, introduced into the stomach, are found in the 

 blood, without our being able to discover them in the chy- 

 liferous vessels and the thoracic duct. Friction on the skin, 

 and the peristaltic motion of the bowels, in this way aid 

 absorption by promoting the movement of the liquids in 

 the vessels. 



Exhalation. The function of exhalation is, in general, 

 effected by the same mechanism, and under the same laws 

 as those of absorption. Through the coats of a vessel, 

 capable of imbibing the contained liquid, a portion of it is 



* The fact is alluded to by Dr. Faraday (Experimental Researches in 

 Electricity, 13th series, 1646.,) and has been made the subject of a paper 

 by Mr. James Napier (On Electrical Endosmose ; in the Memoirs and 

 Proceedings of the Chemical Society, vol. iii. p. 28.) J. P. 



