58 CDBRENT FORCE CHAP. V. 



To decide this point, let us just observe we have 

 two facts before us. First, the venous blood in- 

 dicates a positive condition ; and, secondly, the chyle 

 also indicates a similar state. Now if any difference 

 exists between these two fluids, we shall detect it by 

 inserting the electrodes, one into the vein, and the 

 other into a lacteal; but upon doing so no effect" 

 occurs upon the needle. This experiment is the very 

 counterpart to those of Pouillet and Mullee, when 

 they inserted the electrodes into the vein and artery 

 of a living animal without observing any action upon 

 the galvanometer, and to which I have already alluded. 

 This negative result would only prove that the chyle 

 and the venous blood are in the same electric states ; 

 and all that can be said in regard to the experiments 

 we are now considering is this, that the effect, 

 the positive state as indicated by the needle, may be 

 due partly to the positive state of the chyle, and 

 partly to that of the venous blood which is conducted 

 by the mesentery. 



From what has been already remarked in regard 



■= It must not be supposed that no effect is always obtained 

 under these circumstances. It is difficult and ahuost im- 

 possible, in these physiological experiments, not to obtain some 

 slight effect upon the needle; but any one, after a little 

 experience, would even be enabled to ascertain the marked 

 difference between a decided and definite action upon the 

 galvanometer, due to a definite and permanent cause, and that 

 which might arise &om some slight and variable circumstance, 

 such as a difference in the state of the parts as regards 

 moisture, and as to the contents of the intestines, &c. 



