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 



*Vn* * P * O o* oVo0 * 



!:"; i ooj!f ?.? 



0*o * " io*0 O 



.o . .; ;<,;<> o v . ," 



o *o <">*,, of,"" o*o o 



'f&'&W c!f.>.o> Xo i;. . j; 



O o ocT oo * *o 



00 



o o o o o o oo ooo oVo o o o o oo o o o 



000 o o O o o So O 



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 hypothesis 

 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 



