ELECTRO-PHYSIOLOGY CHAP. 



first degree, to be regarded as chemical, and that " the true 

 chemical nature of vital processes must not be overlooked in 

 their physical symptoms" (24, p. 59). Hering has developed 

 upon the most general grounds, and, as it were, in final 

 consequence of his physiology of the senses, a theory of the 

 functions of living matter (more particularly under electrical 

 excitation), which, though as yet little recognised, is really the 

 most comprehensive expression of all the data relating to this 

 department. By it he is able to derive and to explain all facts 

 quite simply from a few fundamental postulates of metabolism. 

 Hering starts with the proposition that, when a muscle or nerve 

 is longitudinally traversed by current, the excitable substance is 

 altered in an opposite sense at the physiological anode and kathode : 

 more correctly, antagonistic alterations in the chemical state of 

 the substance are set up at the two poles since at all points by 

 which current enters the uninjured living matter, the assimilatory 

 process preponderates, and (to use Hering's expression, cf. p. 71 f.) 

 effects an " allonomous ascending" alteration, while dissimilation 

 (disintegration) prevails at the collective points of exit, inducing 

 " allonomous descending " alteration. Every excitation, in the 

 ordinary sense of the word, is undoubtedly characterised by the 

 predominance of the dissimilatory process, it being immaterial 

 whether this process is confined to its seat of origin, or propagated 

 further by conduction. Under all circumstances, therefore, the 

 physiological kathode is the seat of excitation lasting throughout 

 the closure of the current, the closing excitation. Hering's 

 account of the processes at the anode, developed as the corollary 

 to his theory of visual sensation, is less obvious. 



" Just as we may conceive of external stimuli which compel 

 the living substance to vigorous dissimilation, so others are 

 conceivable which enforce greater activity of assimilation. This 

 increase of assimilation, which is no longer purely autonomous, 

 and is not balanced by corresponding activity of dissimilation, 

 modifies the living matter in a direction contrary to that 

 described above as ' below par', and therefore to be denoted ' above 

 par.' At the close of such excitation the living matter is over- 

 nourished ; its disposition to assimilation is less than before, in 

 ratio with the intensity and duration of stimulus, and the 

 corresponding preponderance of allonomous assimilation over 

 autonomous dissimilation the disposition to dissimilation is pro- 



