40 
PATHOLOGY. 
phyfiological learning, of which many of his fpeculations 
betray a fad deficiency. 
In regard to fever, Dr. Cullen’s theory was that the 
firft change induced in the animal fyftem by the opera¬ 
tion of the exciting caufes of fever is, “ diminution of 
the energy of the brain.” The powers of the body and 
the mind, the functions of fenfation and motion, refpi- 
ration, circulation, and fecretion, all fail, or are dimi- 
niflied in the general debility ; but, after a certain time, 
a morbid increafe of fome of thefe funftions, efpecially 
of the circulation, takes place, with an augmentation of 
the heat. The three Hates of debility, of cold, and of 
heat, which regularly fucceed each other in fever, in the 
order juft mentioned, are prefumed to exift in the rela¬ 
tion of caufe and effedt; the firft ftate being the refult of 
the fedative or debilitating influence of contagion, rnarfh- 
miafmata, and cold, which are the exciting caufes. Dr. 
Cullen acknowledges his inability to explain fatisfadlo- 
rily, how the debility produces all the phenomena of 
the cold ftage, efpecially the Jpafmodic conllridtion of the 
extreme arterial veflels, which is inferred from the luf- 
penfion of the fecretions, and the flirinking of parts, in 
the cold ftage, as well as from the continuance of this 
fufpenfion in the hot ftage, after the aftion of the heart 
and large arteries is increafed. Were the conftridHon of 
the cold ftage merely the refult of the weakened adfion 
of the heart, it is fuppofed, that, on the return of its 
ordinary or increafed adtion, the conftridfion would be 
removed, and the fecretions reftored. Here Dr. Cullen 
reforts to “ the vis medicatrix nature, fo famous in the 
fchools of phyfic i. e. the innate preferving power of 
the conftitution, which has been appealed to for the fo- 
Jution of difficulties by all medical theorifts, from Hip¬ 
pocrates downwards. This “ fpafm of the extreme vef- 
fels,” then, is confidered as “ a part of the operation of 
the vis medicatrix naturae j” at the fame time, Dr. Cullen 
is of opinion that, during the whole courfe of fever, 
there is an atony exifting in the extreme veflels, depend¬ 
ing on the diminifhed energy of the brain, and that the 
relaxation of the fpafm requires the reftoration of the 
tone and adtion of thefe. To this atony in the veflels of 
the fkin, he attributes the lofs of appetite, naufea, and 
vomiting, the ftomach being affedted by fympathy. The 
fpafm induced in the extreme veflels throws a load of 
blood upon the central parts of the circulating fyftem, 
which proves a fource of irritation to the heart and ar¬ 
teries, and excites them to a greater adtion, which con¬ 
tinues till the fpafm is relaxed or overcome. The hy- 
pothefis is thus briefly recapitulated : “ Upon the whole, 
our dodlrine of fever is explicitly this. The remote 
caufes are certain fedative powers applied to the nervous 
fyftem, which, diminiftiing the energy of the brain, 
thereby produce a debility in the whole of the fundlions, 
and particularly in the adtion of the extreme veflels. 
Such, however, is, at the fame time, the nature of the 
animal economy, that this debility proves an indiredt 
ftimulus to the fanguiferous fyftem ; whence, by the in¬ 
tervention of the cold ftage, and fpafm connedted with 
it, the adtion of the heart and large arteries is increafed, 
and continues fo till it has had the effedt of reftoring the 
energy of the brain, of extending this energy to the ex¬ 
treme veflels, of reftoring therefore their adtion, and 
thereby efpecially removing the fpafm affedting them ; 
upon the removing of which, the excretion of fweat, and 
other marks of the relaxation of excretories, take place.” 
Cullen’s Firft Lines, § 46. 
To this theory it has been objedted, firftly, that it is 
founded, as far as regards the vis medicatrix natures, on 
the gratuitous affumption that a principle exifts of which 
we have fenfible evidence ; fecondly, that, to take the 
cold ftage as the proximate caufe of the after-phenomena 
of fever, is difl'onant with evident fact; for the hot ftage 
of fever often comes on apparently from external caufes, 
and unaccompanied by the cold ftage; and thirdly, that, 
with regard to fpafm of the external veflels, 1'uch an oc¬ 
currence affords no explanation of febrile phenomena; 
and indeed it feems quite abfurd to fuppofe that the hot 
ftage and the cold ftage can by any means be confequences 
of the fame adfion ; and that, fo far from the capillaries 
being contradfed, we have pretty clear evidence tha"t 
they are extremely diftended with blood during all febrile 
difeafes in which the fkin is affedted. 
In a paflage of his “ Inftitutions of Phyfiology,” Cullen 
fpeaks of a ftate of excitement, or collapfe, of the brain and 
nervous fyftem, on which he fuppofes the ftrength or 
debility of the other parts of the body to depend; and 
in his other writings, he is constantly labouring to prove 
ill what manner thefe conditions may be occafioned by 
the agency of various caufes. Brorcn, feizing upon this 
idea, let about the formation of a new theory, according 
to which all the adtions of life were to be referred to the 
excitement of the body by Jlimuli, and all difeafes reduced 
to the two general heads of diredl and indiredl debility, or 
debility ariling from a deficiency, or a previous exoefs, 
of excitement j or in other words into fthenic and afthe- 
nic diforders. 
The Brunonian fyftem might very well be compared 
with the Methodic, its diftinguilhing features being the 
referring of all difeafes to two oppofite conditions of the 
conftitution, Jlhenia and ajlhenia, or ftrength and debility, 
which might with almoft equal propriety have been called 
Jlridlum and laxum, (fee p. 11.) and the confequent ex- 
clufion of all particular inveftigation of the minute dif- 
tindtions in the phenomena of difeafes which it encou¬ 
raged. 
This fweeping arrangement was, however, much 
lauded in many parts of the continent, and gained a very 
large proportion of advocates in our country, among 
thofe who had not fufficient knowledge of nature to de- 
tedt its fallacy. The molt general of Brown’s principles 
are thus explained. 
1. To every animated being is allotted a certain portion 
only of the quality or principle on which the phenomena 
of life depend. This principle is denominated excit- 
ability. 
2. The excitability varies in different animals, and in 
the fame animal at different times. As it is more in- 
tenfe, the animal is more vivacious or more fufceptible 
of the adfion of exciting powers. 
5. Exciting powers may be referred to two clafles. 
1. External; as heat, food, wine, poifons, contagions, 
the blood, fecreted fluids, and air. 2. Internal; as the 
functions of the body itfelf, mufcular exertion, thinking, 
emotion, and paflion. 
4. Life is a forced ftate; if the exciting powers are 
withdrawn, death enfues as certainly as when the excit¬ 
ability is gone. 
5. The excitement may be too great, too fmall, or in 
juft meafure. 
6 . By too great excitement, weaknefs is induced, 
becaufe the excitability becomes defective ; this is indi¬ 
rect debility : when the exciting powers of ftimulants are 
withheld, weaknefs is induced; and this is diredt debility. 
Here the excitability is in excefs. 
7. Every power that adts on the living frame is ftimulant, 
or produces excitement by expendingexcitability. Thus, 
although a perfon accuftomed to animal food may grow 
weak if he lives upon vegetables, ftill the vegetable diet can 
only be confidered as producing an effedt the fame in kind 
with animal, though inferior in degree. Whatever powers, 
therefore, we imagine, and however they vary from fuch 
as are habitually applied to produce due excitement, they 
can only weaken the fyftem by urging it into too much 
motion, or fuffering it to fink into languor. 
8. Excitability is feated in the medullary portion of 
the nerves, and in the mufcles. As foon as it is any¬ 
where affedted, it is immediately affedted every-where ; 
nor is the excitement ever increafed in a part, while it is 
generally diminifhed in the fyftem; in other words, dif¬ 
ferent parts can never be in oppofite ftates of excitement. 
We 
