418 On the Nervous Impulse in different Individuals. [Oct. 20, 



The results here recorded have an additional theoretical interest 

 when considered in connection with the recently published work of 

 Boycott.* This observer showed that in the sciatic of the frog the 

 number of nodes of Ranvier is very approximately constant, and 

 is independent of the length of the frog (33*2 in twenty-six frogs), and 

 that the length of the internodes differs considerably, ranging from a 

 length of 1803/x in large frogs to 249/x in small. Per unit length there- 

 fore there are many more nodes of Ranvier in the sciatic of a small 

 than in that of a large frog, and as the present measurements show 

 that the rapidity of the nerve impulse is the same in both classes of 

 frogs, it follows that the nodes of Ranvier are without any influence on this 

 rapidity, and that the internode cannot be regarded in the light of a 

 functional unit in this connection. 



As the length of the internode is proportional, both to the length of 

 the whole nerve and to its diameter, it is riot unreasonable to infer that 

 this visible pattern furnishes a scale by which the invisible ultra- 

 microscopic structure of the nerve-fibre can be estimated. It has been 

 shown above that the scale of the visible pattern is without effect 

 on the rate of the nervous impulse, it follows that the size of the 

 invisible structure is also without effect, and this will modify such 

 theories of nerve propagation as take this latter into account. 



It gives me much pleasure to acknowledge the kind advice and 

 assistance I have received from Dr. Waller in the prosecution of this 

 research, and also to return my thanks to the gentlemen who lent 

 themselves to the purpose of my experiments. 



Conclusions. 



(1) The rapidity of the nervous impulse per unit length is the same 

 whatever be the stature of the individual. 



(2) The time taken by this impulse to travel from the centre to the 

 periphery is greater in taller individuals. 



(3) The nodes of Ranvier exercise no influence on the rate of 

 impulse. 



* Boycott, 'Journal of Physiology ' (in the Press). 



