746 
DR. CARPENTER ON THE MUTUAL RELATIONS OF 
degree of nervous power exerted, will be (the author believes) disputed by no physio- 
logist ; it is most remarkably illustrated in the extraordinary force developed under 
the influence of emotional excitement, which often calls forth a much greater measure 
of muscular power than the will can command. 
Of the relations between Magnetism and the nervous force, the author thinks it 
preferable to say nothing more at present, than that various indications appear to 
him to be afforded, by recent investigations, of the existence of a direct and influential 
connection*. 
The relation thus pointed out between Nervous agency and the various Physical 
forces, is the more remarkable, when it is considered that the nervous power must be 
regarded as the highest of all the forms of vital force, both in its relations to mental 
action, and in its dominant power over organic processes of every kind. Considering 
how closely, as already pointed out, it is correlated to the forces concerned in mus- 
cular and ciliary movement -f', in nutrition and secretion, in development and repro- 
duction, it cannot be thought improbable that what is true of it should be true of 
them also ; and that a relation of mutual convertibility should exist between these 
and one or more of the physical forces. Such relations the author believes to exist ; 
and he now proceeds to adduce facts which appear to him adequate to support that 
belief. 
The muscular force may be called forth, as is well known, by electricity directly 
applied to the muscle itself; by heat, cold, and chemical agents; and by mechanical 
irritation. These agencies, however, do not appear so directly concerned in the produc- 
tion of the motor power, as in occasioning that metamorphosis of living organized tissue 
into chemical compounds, whereon the development of the muscular force seems to be 
immediately dependent. It is now universally admitted that the disintegration of a 
certain amount of muscular tissue, and the new arrangement of its components in 
combination with oxygen supplied by the blood, is necessary for the development of 
its contractile force ; and the considerations adduced by Prof. Liebig render it highly 
probable, that the muscular contraction may be regarded as proceeding from the ex- 
penditure or metamorphosis of the cell-force, which ceases to exist as a vital power, 
in giving rise to mechanical agency. The amount of muscular force developed ap- 
pears to bear an exact correspondence with the amount of urea formed by the meta- 
morphosis of the muscular tissue ; and this metamorphosis involves the cessation of 
its existence as a living structure, and consequently the annihilation of the vital 
* Whatever scientific value we might have otherwise been disposed to attach to the researches of Baron von 
Reichenbach on “ Magnetism, Crystallization, &c. in their relations to Vital Force,” they seem to derive some 
additional claims on our attention from the discoveries of Prof. Faraday in regard to the universal operation of 
the magnetic force, and its relations to light and to the polar force of crystals, — discoveries which, be it ob- 
served, had not been made when the phenomena observed by Baron von Reichenbach were first made public. 
t In man and the higher animals, the ciliary movement does not appear to be in any degree controllable 
by nervous agency ; but there can scarcely be a doubt that in the Rotifera it is thus governed. 
