138 IRRITABILITY 



the entire number of molecules capable of disintegration do not 

 break down, but only a certain per cent, of the same, then it would 

 not be possible to conceive of a molecular structure of the nerve 

 in which this would take place without decrement of the wave of 

 excitation. With the assumption of a generally homogeneous 

 molecular structure (Figure 23, a) of the elementary fibers it 



Fig. 23. 



would be entirely incomprehensible how, with the decrementless 

 extension of the excitation, individual molecules capable of break- 

 ing down could escape disintegration. If, on the contrary, the 

 molecular structure is not homogeneous it only is possible to 

 explain a conduction, on each cross section of which an equal 

 per cent, of irritable molecules break down, by the h)rpothesis 

 that the irritable molecules are in their turn ordered in fiber- 

 shaped series (Figure 23, b) within the elementary fiber and are 

 thus protected to a certain degree from one another and from 

 transverse conduction of excitation. This hypothesis would, 

 therefore, only mean that the elementary fiber is not such in 



