500 SCIENCE PROGRESS 



has conceived a physico-chemical explanation of the nature of 

 the state of colloid solution, and of the nature of the nervous 

 impulse. The molecules capable of entering the state of colloid 

 solution are possessed of pairs of unsatisfied valencies carr3^ing 

 equal quantities of electrical charge of opposite sign. B}^ reason 

 of this quality these molecules can unite with one another to 

 form giant molecules in which the original units are seen as 

 " semplars " joined end to end or side to side, forming a long 

 frame, around which and in the interstices of which the solvent 

 lies. These giant molecules, and the core of the nerve-fibre 

 is one such, being elastic respond to a shearing strain by the 

 transmission of motion along the mass of the molecule. This 

 transmitted state represents the nervous impulse, and at first 

 apparentl}' by a purely mechanical conception. But in the 

 propagation of this strain opposite electrical charges are 

 supposed in each segment of the molecule to be moved one 

 upon the other. Upon such a basis Sutherland has worked 

 out the probable rate of transmission of such a process, and 

 finds it of the same order as the transmission rate of the 

 nervous impulse. To me it seems that the mathematical treat- 

 ment of this hypothesis involves considerations of exactly the 

 same rank as those involved in the hypothesis I have advanced. 

 The alteration supposed to occur in the colloid aggregates 

 compares with the molar charges assumed to occur in the frame- 

 work of the giant molecule, and there is the exactly analogous 

 displacement of electrical charges, and in both cases that is all. 



Should Sutherland's conception of the nature of the nervous 

 impulse, or should mine, appear too bald or too far removed 

 from considerations of biological rank, I would suggest that 

 this function of transmitting change is of all the functions of 

 living matter the most widespread and the most simple. It 

 is probable that a similar change is transmissible within the 

 limits of every cell in the body. This fact — and I w^ould make 

 bold to say that it is a fact — is frequently lost sight of in 

 admiration of the complex results obtained as a consequence 

 of the transmission of these changes into districts where more 

 complex happenings occur. The conduction of nervous impulses 

 is sometimes discussed side by side with the precise value of 

 states of consciousness, although there is no evidence that the 

 actual process by which change is propagated has altered in the 

 course of development from the protozoon to man. 



