THE VITAIj and PHYSICAL FORCES. 
741 
elsewhere, — so may nerve-force, which has its origin in cell-formation, excite or modify 
the process of cell-formation in other parts, and thus influence all the vital manifesta- 
tions of the several tissues, whatever may he their own individual characters. And 
this expression will also be found available for the well-known influence of mental 
conditions upon the properties of the various tissues and secretions, since this influ- 
ence can only be exerted through the medium of nervous agency. Further, it not 
only appears that a simple withdrawal or disturbance of the nervous force supplied 
to particular organs occasions a retardation or perversion of their vital operations ; 
but there also seems evidence that an influence of an opposite hind may be transmit- 
ted through the nervous system, which is positively and directly antagonistic to the 
vital powers of the several tissues and organs ; — such, at least, appears to be the only 
mode of accounting for the extraordinary effect of a shock, mechanical or mental, in 
at once and completely destroying the contractility of the heart, and in immediately 
bringing to a stand the vital operations of other parts; and it harmonizes well with 
the fact that, in hemiplegia, the “ palsy-stroke” transmitted from the brain along the 
spinal cord almost invariably affects the leg less injuriously than the arm, and for a 
shorter duration, recovery first taking place in the leg, even when it has been at first 
paralysed as completely as the arm. If the nervous force be regarded as a polar 
force (as suggested by Messrs. Todd and Bowman, ‘ Physiological Anatomy,’ vol. i. 
p. 237 seq.), analogous in its mode of transmission to electricity or galvanism, it 
is not difficult to understand that the reversal of the usual direction of its action may 
produce the effects in question, regard being had to the opposite effects shown by 
Prof. Matteucci to be produced upon nervous excitability by the direct and the in- 
verse electric currents 
It is hoped that the foregoing considerations (in support of which many others 
might be adduced 'f~) will have served to establish the general proposition, that so 
close a mutual relation exists between all the vital forces, that they may be legiti- 
mately regarded as inodes of one and the same force. The most general and charac- 
teristic of the manifestations of this force, which serves to unite and connect all the 
rest, is that which is concerned in cell-formation ; and to this act, many of the 
other agencies appear to be essentially related. Thus the tissue of a muscle is 
constructed solely with a view to its manifestation of contractile power; whilst the 
development of nervous matter has reference entirely to the peculiar operations in 
which it is to be concerned. We find only one kind of tissue serving for the genera- 
tion and transmission of nervous power ; this alone affording the material substratum 
through which the vital force can manifest itself as nervous agency. And so, in like 
manner, it can scarcely be doubted that the contractile tissues, the assimilating cells, 
* Lectures on the Physical Phenomena of Living Beings, translated by Dr. Pereira, p. 262. 
t The dynamical relations of the nerve-force to mental agency, on the one hand, and to the several vital 
forces on the other, constitute a field of inquiry of vast extent and profound interest. To this inquiry the au- 
thor purposes to apply himself, should the views enunciated in this paper be accepted as true, or even probable, 
by those most competent to judge of their merits. 
