CHAP. IV. §. IV. DUEING MAMMARY SECRETION. 45 



the electrode in contact with the vein is positive to 

 the other 8° or 10°. 



Here, in this instance, we get evidence of the 

 secreted product {the milk) and the venom blood being 

 in opposite electric states. 



It will now be seen, from the foregoing expe- 

 riments, that wherever secretion occurs, whether in 

 the stomach and intestines, in the liver, in the 

 kidneys, or in the mammary gland, it will be found 

 that the act itself is not only accompanied with the 

 manifestation of current force, but that the venous 

 blood is also, in all these instances, in the same 

 state, in a positive electric state. The next question 

 that would naturally arise is the following : What is 

 the state of the arterial blood? Although it has 

 been found that the arterial blood indicates a positive 

 state when formed into a circuit with the secreted 

 product, the other necessary element, viz. its electro- 

 negative element, the cation, for example, has not yet 

 been obtained. Eeasoning from analogy, it is in 

 the lungs that a satisfactory explanation on this 

 point must be sought for. 



Physiologists may not perhaps be disposed to 

 adinit that the function of the lungs corresponds to 

 tha,t of a secretory organ; or that the process by 

 which carbonic acid is eliminated from the blood 

 corresponds to that by which the acid is eliminated 

 from the stomach ; fortunately a decision on this 

 point will not be necessary, and therefore need not 



