80 
PATHOLOGY. 
confidered is the nervous. It confifts of the cranial brain, 
the fpinal marrow, nerves, and ganglia. By means of 
this fyftem, all mental emotions are communicated to the 
other parts of the animal frame, and, through its medium, 
all external impreflions are communicated to the mind. 
We obferve likewife a fibrous ftruCture of different kinds 
in various parts; as mufcular, offeous, &c. the moil ge¬ 
neral and important of which are the mufcular ones. To 
thefe is added a fundamental cellular ftruCture, which ap¬ 
pears to conneCt all parts of the other fyftems together; 
and which has various appearances in regard to diverfity of 
fubftance, and indeed in regard to the fecretions derived 
from it. The union of thefe three fyftems takes place in 
various modes: in fome cafes in tubes, or on membranes, 
See. Sec. and the more remarkable of thefe unifons may 
be aptly divided into the digeftive, refpiratory, fanguife- 
rous, fecernent, and abforbent, fyltems; and this phyliolo- 
gical division we have taken as the bafis of our arrange¬ 
ment, which agrees with the excellent one lately made 
by Dr. Good, in his Phyfiological Syltem of Nofology. 
Many objections have been made however to all the 
prefent arrangements; the mod important of which is, 
that, by allowing the attention of the medical practitioner 
to be exclulively directed to one fyftem or to one organ, 
it prevents that due attention being paid to morbid cate¬ 
nations, which the practice of phytic imperioufly de¬ 
mands. There is nothing, however, in the nature of 
- nofology which renders this error a venial one. It mull 
be allowed that morbid impreflions are generally' primarily 
made on one particular tilTue or organ; and it mull be 
allowed too, that a fyftem which is fecondarily affeCted, 
often fuffers the moft feverely ; or that the fyftem fecon¬ 
darily affeCted may-be the moft important to life, and 
hence our attention fhould be chiefly direCted towards it. 
We will however venture to affert, that whoever has affidu- 
oufly ftudied the ftruCture of parts and their phyfiology, 
cannot fall into the error of confining his attention to one 
part of the animal economy to the exclufion of the reft. 
To render this more plain, we (hall proceed with fome 
further account of the aCtion of the different fyftems 
above mentioned upon each other. If the animal frame 
were fo conftruCted that no inteftinal motion was necef- 
fary for the continuance of its external aCtions, we could 
readily fuppofe it poflible that the nerves would be unaf- 
feCted by any change in the mufcular fyftem, and the 
latter might produce its functions without any impreilion 
from the former. But, when we fee, that the cerebral 
functions can only be continued while blood, pofleffing 
certain properties and component parts, circulates accor¬ 
ding to given-laws through its fubftance; and when we 
coniider that the mufcular fyftem can be called into ac¬ 
tion only by the nervous fyftem, either direCtly by means 
of nerves, or indirectly by fluids, deriving fome of their 
properties from the nerves; then we cannot fail to have 
the moft certain conviction of the aCtion of the one on 
the other. 
It is extremely difficult to know at what part to begin 
fil'd, when fpeaking of aCtions which are thus always de¬ 
pendent one on the other, and which are always in a 
circle. We take, however, the heart ; and, fuppofing 
it of a fibrous fundamental ftruCture, and fupplied with 
blood and nerves, we proceed to confider its aCtion. A 
cavity of the heart called the left ventricle, having received 
a certain fupply of blood, propels it by contraction into 
the aorta, and from it into the fmaller arterial branches. 
Thefe branches further aflift the motion of the blood by 
contracting their circumference, the power of contrac¬ 
tion being in an inverfe ratio to the diameter of the tubes. 
The terminations of arteries are further affifted in pro¬ 
pelling the blood by' the property of capillary attraction ; 
reins reftore the fluid to the heart in a direCt ftream, al¬ 
tered however in its properties; for veflels called Jeccr- 
nents have, by means of an affinity exifting between* their 
coats and certain parts of blood, removed fome parts of 
that fluid ; and other veflels, called abforbents, have re- 
ftored a portion of other component parts previoufly fe- 
creted from the blood, or received from without. The 
moft obvious change undergone during this circulation 
is a-change in the colour of the blood ; this however is 
reftored by fecond circulation produced by the other ca¬ 
vities of the heart, and is called the pulmonary procefs. 
In this circulation the blood appears to be indireCtly ap¬ 
plied to atmofpheric air, and hence to acquire a principle 
which reftores its colour. But this procefs is under the 
immediate influence of the nervous fyftem, and is difeon- 
tinued when the aCtion of that fyftem is fufpended. 
After this procefs has taken place, the blood is reftored 
in its priftine ftate to the heart. The changes which fe- 
cretion and abforption effeCt in the blood are of courfe 
depravation of its elements on the one hand, and repro¬ 
duction on the other. Secretion has been defined “ a pro¬ 
cefs which feparates from the blood fubftances which are 
not found in that fluid.” This propofition, as it Hands, 
is fo abfurd, that we ihall take no pains to confute it. 
Secretion is better explained by fuppofing that it deprives 
the blood of certain of its elements, and combines them 
in a manner different from that in which they previoufly 
exifted in that fluid; and further, that our chemical ana- 
lyfis is not fufficiently accurate to deteCt the elements 
(ftriCtly fpeaking) of this re-compofition. 
The number of the various fecretions is too great to 
be here detailed. Some of them are re-abforbed, and fome 
pafs from the body by various outlets. Previous to thefe 
circumftances, however, their progrefs is retarded, and 
their nature changed, by fubftances called glands. The 
abforbents receive thefe fecretions from the whole funda¬ 
mental or cellular ftruCture ; they receive the fluid previ¬ 
oufly fecreted from the blood; they further receive from 
certain expanfions of the fundamental or cellular ftruC¬ 
ture extraneous bodies. Thefe are, the (kin, the lining 
of the pulmonary air-cavities, and the alimentary canal. 
The abiorption from the (kin is in general probably final!; 
though, when internal abforption is deficient, cutaneous 
abforption is no doubt increafed. Of the pulmonary cavi¬ 
ties the foreign matter abforbed is derived from the air. 
The nature of this abforbed matter is not precifely known : 
It is indifpenfably neceffary, however, to the performance 
of life. But, the greateft portion of extraneous matter 
is abforbed from the alimentary canal. The whole of this 
canal is perhaps an abforbing as well as fecreting furface; 
a peculiar portion of it is however much more aClive than 
the reft ; and this portion is placed fo far down, that the fo¬ 
reign bodies received have had time to fuffer the changes 
induced by the fecretions poured into the canal, and 
thereby to have its nutritive part feparated from that ex- 
crementitious mafs. The great extent of this expanfion, 
its numerous fecretions, the clofe relation it holds with 
the nervous, its intimate relation with the vafcular, fyf¬ 
tem, and by their means indireCtly with every part of 
the body, render it perhaps the moft frequent medium of 
general difturbance in the human frame; and hence it 
may with great propriety be confidered in the firft part 
of our pathological difq uifitions. 
The view' we have taken of the human frame clearly 
indicates the iinpoffibility of ever forming a nofology in 
the old and reltriCted ufe of the term ; that is, an arrange¬ 
ment of difeafes founded on the affumptioh that an indi¬ 
vidual part or a feparate, ftruCture can be difordered 
without involving the reciprocal aCtion of various other 
parts. When the phyfician, therefore, finds fever ar¬ 
ranged under the clafs Hasinatica, he is not to fuppofe 
that we are difinclined to admit the important part which 
the nervous fyftem has in this difeafefand foon of many 
other orders, genera, and fpecies. 
In this place we mult recur to our article Nosology, 
in order to offer fome apology to our readers for neglect¬ 
ing to redeem our promile of tiling Cullen’s fyftem. We 
trult this promife will be deemed better “honoured in 
the breach than in the obfervance,” when it is confidered, 
that many errors had been complained of in Cullen’s 
3 arrangement. 
