THE PROCESS OF EXCITATION 93 



affected by stimulation, consists as demonstrated in increase 

 of formation of carbon dioxide and water, and in the disintegra- 

 tion of the nitrogen-free groups. The innumerable observations 

 on metabolism during the stage of the activity of the muscle, as 

 those of Hermann, v. Frey, Fletcher, Johannson, Thunherg, 

 and many others on the individual muscle, and those by Voit, 

 Fick and Wislicenus, Pfluger, Rubner, Zuntz, Lehmann and 

 Hagemann, Bernstein and Lowy and others on the muscle of the 

 entire organisms, have sufficiently proved this fact. However, we 

 should not apply in detail the conditions existing in the muscle 

 to all living substance. Comparative methods show us, rather, 

 that the functional portion of metabolism is very differently 

 involved in various forms of living substance. The formation of 

 carbon dioxide and water is constant in nearly all forms of living 

 substance. We must, however, exclude certain micro-organisms, 

 which have adapted themselves to unusual vital conditions. 

 Further, there appear in some forms manifold special constit- 

 uent processes consisting in a disintegration of living substance 

 which are in part converted into very complex combinations. In 

 the gland cells this type is represented in an especially high degree. 

 Here the functional disintegration leads to excretion of proteins, 

 glycoproteins, nucleoproteins, cholic acid, enzymes of various 

 kinds, all of which are complex and at the same time nitrogenous 

 organic combinations. This fact must not be lost sight of. The 

 origin of these special members, however, for the present is com- 

 pletely unknown, while on the other hand, it is self-evident that 

 the general and constant constituents of the process of excitation 

 must claim a first place in our interest. It is just at this point, 

 therefore, that we must endeavor to penetrate somewhat more 

 deeply into the mechanism of the excitation process and analyze 

 in greater detail the acceleration of the functional constituent 

 parts of metabolism produced by the stimulus bringing about the 

 formation of carbon dioxide and water. 



The question arises : By what means is the particular labile state 

 of just this constituent part of functional metabolism conditioned? 

 The lability of the functional portion of metabolism, excitated 

 by the stimulus, resembles the processes in the disintegration of 



