744 
DR. CARPENTER ON THE MUTUAL RELATIONS OF 
mechanically irritated, or if the nerves proceeding from it be excited to action, even 
after their separation from the central organ, electric manifestations are obtained, 
the intensity of which is proportional to the excitement of nervous power thus effected. 
Various other phenomena recorded by Matteucci make it evident, that the amount 
of electric force generated by the electrical apparatus is in precise accordance with 
the amount of nervous force which is transmitted to it=^. 
Thus it appears that whilst electricity excites nervous force through the instru- 
mentality of the nervous structure, nervous force excites electricity through the in- 
strumentality of the electrical apparatus ; and the case seems to be one which points 
directly to the existence of the same hind of relation between nervous force and elec- 
tricity, as exists between electricity and magnetism, heat, chemical affinity, &c., 
whatever may be the form in which w'e think it best to express our notion of that re- 
lation. No one, the author believes, who has onceaelopted the idea of “ correlation” 
as subsisting among' the physical forces, can look at the peculiar connections to which 
he has adverted, as existing between the nervous and electrical forces, without per- 
ceiving how completely it is applicable to them. And he cannot but think that some 
such idea must have been present to the mind of Prof. Matteucci, although he has 
not met with any distinct expression of it in his writings'!'. 
But Electricity is not the only physical force possessing this peculiar relation to the 
nervous force. 
Our sensations of heat and cold are entirely dependent upon the power which Heat 
possesses of exciting nerve-force in the sensory nerves. Further, if heat be applied 
to a motor nerve in its course, it will call forth muscular contractions; and if ap- 
plied to a sensory nerve, it will occasion sensations, both common and special ; pre- 
cisely after the manner of electricity. Conversely, there are phenomena well known 
to physiologists, which have not yet been explained upon the purely chemical doctrine 
of calorification, and for which it does not seem possible that any such explanation 
can account. Several of these phenomena appear to point to the nervous force as a 
direct agent in the production of heat ; the amount of caloric thus generated being 
* The question whether a disturbance of electric equilibrium occurs during the contraction of a muscle, and 
whether this is to be looked upon as the direct result of the operation of the nervous force, or is consequent 
upon the molecular changes taking place in the muscle under the influence of that force, must he regarded as 
at present suh judice. If the former prove to be the case, we have another instance of the direct production 
of electricity by nervous force ; if the latter, the same metamorphosis would seem to take place through the 
intermediate condition of muscular force. 
f [Since this paper was written, the author has had the satisfaction of learning, from the perusal of Prof. 
Matteucci’s Eighth Series of “Electro-Physiological Researches,” that he has formally adopted the doctrine 
of the correlation between the nervous and electrical forces, which the author had himself put forth, nearly two 
years before, in a review of Prof. Matteucci’s “ Lectures.” (See Brit, and For. Med.-Chir. Review, Jan. 1848, 
p. 232.) In addition to the proofs adduced above. Prof. Matteucci has furnished a new series, arising out of 
the action of an electric current transmitted through a muscle, on the nerves which ramify through it, (See 
p. 296 of the present volume of the Philosophical Transactions.) — Nov. 20th, 1850.] 
