1905. | The Structure and Function of Nerve Fibres. 339 
between neighbouring cells. Minute as it may be, however, there can be no 
doubt as to the loss of energy from each individual cell. 
It is impossible, therefore, to accept the physical theory dealt with here as 
accounting for all of the phenomena observed. That does not seem to me, 
however, a fact detracting in any way from the significance of the statements 
made above. The “head of steam” immediately made use of in the con- 
traction process may, nevertheless, be sought in the sudden removal of 
conditions hitherto restraining the motion of inorganic salts. In the case 
of the transmission process from cell to cell, we may greatly strengthen 
the form of the statement. The condition essential to this transmission 
must almost necessarily be of the kind considered. It is conceivable, 
therefore, that the most interesting elements of the function of the cell 
might be more economically studied when attention is mainly directed to 
the alterations in physical condition occurring within and around it, than 
by a direction of attention to the ground-phenomena of chemical assimilation 
and dissimilation. 
In the case of nerve-conduction, there is least need to place the chemical changes 
of assimilation and dissimilation in the fore-front of an explanation. Such 
changes are undoubtedly facts, but it has still to be proved that they are 
facts requiring primary consideration in connection with characteristics of 
function. In the case of nerve, the amount of external work done is 
infinitesimal. The tissue’s primary duty is the transmission of energy, and 
it accomplishes the purpose of its existence with remarkably little loss. 
The nervous impulse also is transmitted with a rapidity, and with an 
absence of trail, not usually observed in the transmission of chemical change. 
If the nervous impulse is a chemical phenomenon, then it is a most 
marvellous chemical phenomenon. If it is a physical phenomenon, it falls 
at once into a general class of physical phenomena, also leading to the 
transmission of energy from point to point. As a physical phenomenon 
its nature may not be understood, but it is easy to conceive that it soon may 
be understood, and that it will prove to be a simple phenomenon. If it is a 
chemical phenomenon, then it is almost necessary to conceive that it is a 
complex process, obtainable also, only under the most complex conditions. 
There can be no objection, therefore, to the introduction of another physical 
theory of nerve-function, if supported by sufficient evidence to warrant its 
introduction. The more simple the theory, the more likely it is to be true. 
Let us therefore think of an isolated strip of colloid solution containing, and 
capable of containing without suffering precipitation, a large quantity of 
inorganic salts. Let us also grant the existence of a peculiar relation between 
colloid material and inorganic salts of the nature previously described. 
