in LIVING MATTER 87 



alters neither quantitatively nor qualitatively ; we have what 

 Hering terms autonomous equilibrium. 



But, as we have seen, external stimuli are continually acting 

 upon living matter and modifying the state of its metabolism. 

 Hering distinguishes two kinds of stimuli, which differ essentially 

 inter se, inasmuch as the one kind excite the dissimilatory phase 

 (dissimilatory stimuli] and these are more usually noticed 

 while the other kind act by exciting or augmenting the phase of 

 assimilation (assimilatory stimuli]. 



Assuming, then, the action of a dissimilatory stimulus, 

 dissimilation will be increased, and is termed by Hering allono- 

 mous dissimilation : the living substance changes in its quality 

 and quantity, and has a lower energy value (is "below par"). 

 Hering assumes that in proportion as the living matter, under 

 the influence of this stimulus, is excited to increased dissimila- 

 tion, its inherent tendency to the dissimilatory phase diminishes 

 while its inherent tendency to the assimilatory phase increases. 

 Owing to this property, which he terms the internal automatic 

 regulation of living matter, at the close of the dissimilatory 

 stimulus the opposite process of assimilation sets in more 

 vigorously than usual, so that after a certain time the living 

 matter regains the mean energy value of equilibrium (i.e. is " at 

 par " ) towards which it strives the more incessantly, and with 

 so much the greater energy, the farther it is removed from the 

 said equilibrium in the one direction or the other, by the action of 

 external stimuli. 



It may, however, happen that the dissimilatory stimulus does 

 not cease, but persists for an indefinite time ; then in consequence 

 of the diminished dissimilatory activity, and the simultaneous 

 increase in autonomous assimilation, a new state of equilibrium is 

 finally arrived at, which Hering terms allonomous equilibrium, 

 and which prevails so long as the dissimilatory stimulus is acting. 

 The living matter has adapted itself to the prolonged action of the 

 stimulus. 



The same reasoning holds for the action of the assimilatory 

 stimuli, which provoke an increase in the assimilatory process. 



Verworn, in his General Physiology (1895), has developed 

 Hering's doctrine, while he takes Pfiiiger's theory also into 

 consideration. 



" Pfliiger's assumption of living protein, which distinguishes 

 living cell-substances from dead, and in the loose constitution of 

 which lies the essence of life, is necessitated. But this substance 

 must be of essentially different composition from dead protein, 

 although, as follows from the character of its decomposition - 

 products, certain characteristic atomic groups of the proteins 

 are contained in it. The great lability that distinguishes it 

 from other proteins, can be conditioned only by an essentially 



