30 CUEBENT FOBOE CHAP. IV. §. I. 



are brought into contact one with the mucous surface of 

 the intestine in a living or recently-killed animal, and 

 the other with the venous blood from the same part, an 

 effect occurs upon the needle indicating the secreted 

 product and the venous blood to he in opposite electric 

 states. 



The amount of deflection of the needle would 

 vary according to the delicacy of the instrument 

 employed ; with an ordinary galvanometer, consisting 

 of hut few coils, the deflection was from 3° to 8° 

 or 10°. 



When the electrode, instead of being in contact 

 with the venous Wood, is in contact with the arterial 

 blood, or the surface of the mesentery, the effects 

 upon the needle are the same, as far as the direction 

 of the current is concerned, but the amoxmt of 

 deflection may not be so great. 



Let us now endeavour to explain these results 

 according to known actions, such as the chemical 

 reaction of two fluids upon each other, or to the 

 heterogeneity of fluids, as it is sometimes called. If, 

 for example, a glass cell be taken having a porous 

 diaphragm in its middle, such as a piece of mem- 

 brane, so as to divide it into two cells, and into one 

 compartment we pour an acid solution, and into the 

 other an alkaline solution, and then dip the platinum 

 electrodes of a galvanometer into each of these cells, 

 an effect upon the needle is produced indicating the 

 electrode dipping in the acid solution to be positive 

 to the other. These facts, which have been well 



