194 
P A T H O 
tion, may be chiefly attributed to the irritated ftate of 
the nerves. And accordingly we find, as Mr. Hunter’s 
well-known experiments teftify, that the heat of inter¬ 
nal parts (to which the office of extricating heat does not 
belong) have not their temperature increafed during in¬ 
flammation. It is worthy of remark, that the real in- 
creafe of heat in the inflamed part is not fo great as the 
feelings of the fuft'erer might lead us to fuppofe, the 
thermometer feldom indicating very remarkable changes 
in this refpeft. To the irritated ftate of the nerves we 
muff: therefore look for this fenfation of exalted tempe¬ 
rature. 
Mr. Hunter’s account of the rednefs of the part feems 
very probable, efpecially if we add to what he has (aid 
on the fubjeft, that the total want of fecretion muff pre¬ 
vent the chemical change on which the darkened colour 
depends. It appears then, that the tw'o dates of exalted 
fenfibility of nerves on the one hand, and plethora of the 
capillary veflels on the other, account for the four firft 
phenomena of inflammation ; and it would perhaps pre- 
ferve us from much obfcurity in our fpeculations, if we 
afiumed the exiftence of thefe ftates without endeavour¬ 
ing to penetrate into the mode of their production. 
The two ftates of altered nervous fenfibility and al¬ 
tered mufcular or vafcular contraftility, are capable of 
feparate exiftence. Plethora is well known to produce 
fometimes no pain ; and the mod excruciating pain, as 
for inftance in tic doulereux, is often unaccompanied by 
inflammation. In the majority of cafes, however, thefe 
ftates feem to follow each other. The obftruftion of the 
circulation in a limb caufes pain and inflammation ; and 
impreflions w hich can only aft through the medium of 
the nerves caufe the fame aftion. 
The primary impreflions which diforder the properties 
of an artery, mud occur through the medium of the 
nerves, or of the contained blood. From what we 
obferve of the effefts of an undue degree of nervous 
influence being tranfmitted to one part, as in cafes of 
fatigue, &c. we are led to infer, that the exceflive 
tranfmifiion of nervous power brings on two kinds of 
alteration in the contraftility of an artery. It may pro¬ 
duce increafed contraftion; and this will furely be fol¬ 
lowed by fuch a diminution of that force as accords with 
this remarkable and well-known law obferved in con- 
traftile fibres over the whole body; that they, having 
exerted their funftion beyond a certain point, lofe their 
contraftility for a given time. Again ; the nature of the 
nervous impreftion may be fuch as to weaken or direftly 
impair the contraftility of the veil'd, and thus diftention 
of the arteries may occur without any previous contrac¬ 
tion. 
The alterations induced by the bad quality of the 
blood will be of the fame two kinds; a direft diminution 
or direft increafe of the contraftility of the veil'd ; the 
former being lefs uniformly followed by the latter ftate 
than when it arifes from nervous influence. Thefe fafts 
form the bafis of our theory. 
It muft not be forgotten, that this reafoning with re¬ 
gard to the ftate of veflels in inflammation has been 
thought to be overthrown by fome, becaufe it is inade¬ 
quate to explain the various appearances and produfts ; 
as of inflammation, the different cutaneous phlogofes, 
eryfipelas, terminations in gangrene, ulceration, &c. 
And thefe authors have talked of various kinds of inflam¬ 
mation ; as that arifing from different morbid poifons, 
See. To this we reply, that we do not take inflammation 
in this wide fenfe : all we know of the funftion of the 
vafcular fyftem of red blood demonftrates that this (yf- 
tem is capable only of a change of the contraftility of 
its veflels; and no diminution or increafe (and diminu¬ 
tion or increafe are the only changes in contraftility of 
which we can form any clear notion) will account for a 
variety in the appearance of inflammation. We muft 
therefore look to the fecernent fyftem for the various 
forms of inflammation ; and, though the little we know 
LOGY. 
of thefe veflels keeps us ftill much in the dark on the 
fubjeft, yet the phenomena in queftion admit of our 
forming plaufible and general deduftions from the in¬ 
ferred properties of the white veflels. Indeed the effefts 
of inflammation depend much upon the nature of the 
fecretion carried on in particular parts. Thus, when 
inflammation is feated in a mucous furface, (i. e. on a 
furface poflefling veflels which fecrete and pour out mu¬ 
cus,) an increafed quantity of mucous fluid will be 
poured out. When a furface upon which exhalants open 
(or, in other words, a ferous furface) is the feat of in¬ 
flammation, that ftate is, in many inftances, followed by 
increafed flow from thofe veflels. The irritated (fate of 
the nerves alone would difpofe the exhalants to give 
paflage to an increafed quantity of fluid ; and the lame 
eft'eft might refult from Ample plethora. There are 
other fluids which are the produfts of fuch veflels as are 
fituated in an inflamed part. As the blood furnilhes the 
materials for all fuch fluids, fo will the plethoric ftate of 
the blood-vefi’els, during inflammation, furnifn an in¬ 
creafed quantity of thofe materials, while the feparation 
of them from the blood is influenced, or produced, by 
the ftate of the nerves. In each of thefe cafes, we have 
ftrong evidence that the fecernents are the parts pecu- 
liarly affefted, while the ftate of the capillaries is the 
fame; fo that we may conclude, that inflammation is in 
all parts and ftruftures the fame; i. e. a dilatation of 
the capillaries, while its various appearances arife from 
the changes which the fecernents undergo, whether that 
change be in the pouring-forth of unnatural produfts, 
or aflimilating and retaining thofe produfts in their cavi¬ 
ties. In other words, that variety of fecretions is the 
concomitant, not the eflential, circumftance of inflamma¬ 
tion. The fame notion may be extended to furfaces in 
which fecretions are not poured out, but depofited in the 
cellular fubftance ; as eryfipelas, and various unbroken 
cutaneous defcedations. 
We have laid, that diftended capillaries and the ex¬ 
treme fenfibility of nerves account for the four local 
phenomena of inflammation—heat, rednefs, fwelling,and 
pain. We muft not forget to mention, that the diften¬ 
tion of the capillaries is, as Dr. Haftings has (liown, ge¬ 
nerally preceded by increafed aftion or excitement, in 
which the veflels are fmaller, and contraft probably with 
greater frequency. This is fo clearly proved by Dr. H. 
that we (hall not relate his experiments or repeat his ob- 
fervations, but refer the reader to the feries of experi¬ 
ments which he has publilhed (on bronchitis) ; the fa ft: 
is of importance, lince it (hows that excitement, which 
we have been wont toconfider a minor fpecies of inflam¬ 
mation, is really an oppofite procefs. 
The difcufilon of the general phenomena of inflamma¬ 
tion, fever, and the huffy appearance of the blood, re¬ 
quires us to (how in wdiat the ftate denominated Jeter 
confifts, how it is connefted with local inflammation, and 
how a general change in the quality of the circulating 
fluids arifes, from the local inflammation or from the 
general difturbance. 
With regard to the altered quality of the blood, this 
fluid, taken from a patient labouring under inflammation, 
exhibits peculiar appearances. The blood, when it has 
efcaped out of the living veflels, fpontaneoufly feparates 
into two diftinft parts, the ferum and the craffamentum. 
The laft is a compound fubftance, confifting chiefly of 
coagulating lymph and red globules, the molt heavy in¬ 
gredients in the blood. Now it is to be obferved, that 
blood taken away from perfons affefted with inflamma¬ 
tion, is longer in coagulating, and coagulates more firm¬ 
ly, than when drawn from people in other circumftances : 
hence the red globules, which are very heavy, not being 
fo foon entangled in the lymph, defcend by their gravity’ 
more deeply from its furface, which, being in this man¬ 
ner more or lefs divefted of the red colouring matter, is, 
from its appearance, termed the huffy coat , or inflammatory 
cruft , The firmer and more compaft coagulation of the, 
lymph 
