586 
regards their physical properties; and, as ap- 
pears not unreasonable to conclude, capable 
of manifesting a distinct series of vital forces. 
If great strength and power of resistance be 
requisite, a particular form of animal matter 
(gelatine) is united with an earthy material to 
constitute bone; for the developement of 
strength, combined with elasticity or flexibility, 
this same kind of animal matter, or a modifi- 
cation of it, is again employed, containing 
none or a very slight proportion of earthy:ma- 
terial, and forming the various kinds of cartilage 
and ligament; but for the play of the active 
powers of life—for the developement of living 
movements— whether in the performance of 
the nutritive functions, in growth and repro- 
duction, or in the display of muscular force 
and activity, two substances, the most complex 
in chemical constitution of any in the body, 
and possessing the greatest atomic weight, are 
made use of to form the structures, on which 
these remarkable phenomena depend, namely, 
muscle and nerve. These structures are com- 
posed respectively of fibrine and albumen ; 
they are organized in analogous forms, and by 
their mutual reactions they exhibit the mar- 
vellous effects which animal power is capable 
of producing. 
GENERAL OBSERVATIONS ON THE DISPOSITION 
AND COMPOSITION OF THE NERVOUS MAT- 
TER, THE NATURE OF NERVOUS ACTIONS, 
AND THE SUBDIVISIONS OF THE NERVOUS 
SYSTEM. 
The nervous matter presents the singular 
peculiarity that it alone, of all the varied forms 
of animal texture, is directly influenced by the 
mental acts of animals. It is that part of the 
organism through the immediate agency of 
which mind operates upon body and body 
upon mind. rough this connexion with the 
psychical principle of the animal, sensation is 
produced, and volition is enabled to exercise 
its influence on muscular organs. And in the 
whole range of the mysterious phenomena, which 
the student of nature meets with, there is no- 
thing so inscrutable as the fact that the work- 
ings of the mind can disturb and impair the 
organization of the nervous matter; or, on the 
other hand, that the disorganization of the ner- 
vous matter is capable of deranging mental 
manifestations. 
The existence of this remarkable and pe- 
culiar kind of organic matter is limited to the 
animal kingdom, and is therefore one of the 
characteristic features of animals as distin- 
guished from plants. It is obviously the pre- 
sence of a psychical agent controlling and di- 
recting certain bodily acts of animals, which 
has called into existence the particular appa- 
ratus which the nervous matter is employed to 
form. 
In the largest proportion of the animal king- 
dom, the nervous matter is so disposed or 
arran as to form a system complete in 
itself, and distinct from, although connected 
with, the other textures and organs. This is 
called the NERVOUS SYSTEM—the deve- 
lopement of which has always a direct relation 
NERVOUS SYSTEM. 
(Nervous Marrer.) 
to the bodily organization and psychical endow- 
ments of the animal. - 
The nervous matter is accumulated 
masses, forming what are denominated cE 
TREs of nervous actions; and it is also ¢ ve. 
loped in the form of fibres, filaments, or mi. 
nute threads, which, when bound tos 1 
constitute the nerves. The latter an 
ternuncial in their office; they establi 
communication between the nervous ce 
tres and the various parts of the body, anc 
vice vers; they conduct the impulses of the 
centres to the periphery, and carry the img 
sions made upon the peripheral nervous & 
fications to the centres. Nor are the ner 
mere passive instruments in the performance ¢ 
their functions ; but produce their proper 
through their susceptibility to undergo moleeu- 
lar change under the influence of appropriat 
stimuli. ; 
The centres are the great sources of 
vous power; they are the laboratories in 
the nervous force is generated. 
appears to be more immediately cc 
with one of them, which, pre-eminent on thi 
account, exerts a certain control or influenc 
over its fellows. ‘ 
In the centres there are two kinds of ne 
vous matter, distinguished by certain anat 
mica! characters and by certain physiologic 
properties and uses. The one is globular 
vesicular in structure, grey in colour—dyna: 
as regards office. The other is fibrous, its fib 
being tubes containing nervous matter; it 
white in colour, and is devoted to act as 
conductor of impulses to and from the 
matter. The white matter is that of which 
nerves are composed, and the two s 
matter do not occur together any where but 
the nervous centres ; in fact, their ‘co-existe 
in any part of the nervous system is sw 
to constitute that part a centre of nervous act 
In the lowest creatures the existence of 
vous matter is as yet problematical. 
supposed by some physiologists that it is 
fused in a molecular form throughout the 
of the animal, and the muscular tissue 
likewise disposed in a similar way, t 
may act upon the other at ony Pa 
this supposition true, it might be furth 
Tecan that, under such circumstances, 
one kind of nervous matter, the dynamic, ¥ 
exist; for as the office of the white ne 
matter is chiefly to propagate or condi 
distant parts the changes which origin: 
the grey matter, the former would not 1 
queed in animals, in which the elem 0 
the grey matter are in contact with thos 
other textures at every part of the body. 
The form in which nervous matter fir 
velopes itself as a distinct tissue is in 
threads or cords, into the composition 
areolar tissue and bloodvessels gene 
The class of animals in which this arranger 
revails has been designated by Mr. 
ematoneura ; and, in many of these at | 
the existence and the disposition of grey mi 
have yet to be ascertained. » a 
The nervous matter of both kinds is a) 
se 
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