122 



THE ELECTRICAL PHENOMENA Gf MUSCLE 



[CII. XL 



not its electrical sense. Du Bois Beymond explained this by sup- 

 posing that a muscular fibre is built up of molecules, each of which 



FIG. 140. Diagram of the currents in a muscle prism. (Du Bois Reymond.) 



is galvanometrically positive in the centre and galvanometrically 

 negative at both ends. So when a muscle is cut across, a number 

 of the galvanometrically negative ends of these molecules is exposed. 

 On contraction the difference between the centre and ends of each 

 molecule is lessened, and the resultant effect on the whole muscle 

 (made up of such molecules) is similar. 



In the foregoing sentence I have employed the rather cumbrous adjectives, 

 yalvanometrically positive and galvanometrically negative, instead of the terms 

 positive and negative which are usually employed by physiologists. 



If we take a Daniell cell and connect it to a galvanometer, the zinc, as we have 

 seen, is the electro-positive element, and the copper the electro-negative element, 

 but the ends of the wires which connect these metals to the galvanometer have the 

 reverse names ; the kathode or negative pole is connected to the zinc or positive 

 metal ; the anode or positive pole is connected to the copper or negative metal. 

 The current enters the galvanometer by the anode, and leaves it on its way 

 back to the zinc by the kathode. Therefore, although the copper is electro- 

 negative, it may be spoken of as galvanometrically positive, and the zinc though 

 electro-positive, as galvanometrically negative. 



If we apply this to a muscle, we have seen that the current flows (in the wire 

 that connects the uninjured longitudinal surface to the cut end) from the longi- 

 tudinal surface to the cut end ; the longitudinal surface thus corresponds to the 

 copper of the Daniell cell, and is therefore electro-negative, though galvanometrically 

 positive ; similarly the cut end corresponds to the zinc, and is electro-positive though 

 galvanometrically negative. 



The omission of the qualifying prefix to positive and negative has led to a good 

 deal of confusion in physiological writings. A physicist uses the terms positive and 

 negative as meaning electro-positive and electro-negative respectively, and as Dr 

 Waller has pointed out, it is time that physiologists adopted the same nomenclature. 

 In what now follows, I propose to adopt Dr Waller's suggestion. 



There is no doubt about the facts as described by Du Bois 

 Eeymond. We now adopt, however, an entirely different view of 

 their meaning : in causing this revolution of ideas the principal part 

 has been played by Hermann. Hermann showed that the so-called 



