PATHOLOGY. 89 
caufes. The proximate caufes, therefore, of difeafes, 
muft be alinoft as numerous as the difeafes themfelves ; 
and hence they will form part of the pathological dif- 
cuflion we (hall enter into with regard- .to each different 
malady. In this place, however, it will be proper to of¬ 
fer fome remarks concerning the local origin of difeafe. 
That difeafe may, and indeed generally does, arife from 
lofs of the balance of abfion between one part and the fyf- 
tem at large, feems indifputably proved. How far, how¬ 
ever, this part may proceed in difeafed action without 
influencing the general health, is another and an impor¬ 
tant confideration. Having lately met with fome re¬ 
marks on this head by Mr. Pring, we have tranfcribed 
them from his “ Indications,” on account of the clofe 
reafoning with which he has illuftrated the fubjedf. 
“There are but few (perhaps not any) examples of 
difeafe which is confined wholly to one part. There are 
many inftances of difeafe of one part, in which the or¬ 
ganic fyftem elfewhere does not perceptibly fuffer: but 
thefe are attended with pain or difordered motion, which 
is fufficient to prove an extenflon of the difeafed (fate. In 
the organic fyftem, however, a perfon may have an ulcer 
in the leg, or a tumour upon the (boulder, or an herpe¬ 
tic difeafe upon fome fpot of the (kin, or a ftricfure of the 
urethra, &c. without any fenfible derangement of the 
fame fyftem elfewhere. But even in thefe inftances we 
cannot prove that the change is entirely local, unlefs it 
may be fliown, ift, that the natural condition of the feat 
is not a dependent one, by which diforder might origi¬ 
nate in another fphere; and, ad, fuppoflng the difeafe 
fo originate in its apparent feat, that no other is fo con- 
nedled with it as to participate in its modifications. But, 
if it is poflible that any part (hould poflefs only an affimi- 
lating life, that no other part is dependent upon it, and 
that the condition of difeafe does not open any new or 
preternatural relation, then it is poflible that the affimi- 
iating life of fuch part may become exclufively difeafed. 
“ It happens however in moft inftances of difeafe, that 
this ftate prevails in more than one feat. In fuch in¬ 
ftances thefe two alternatives are to be difcriminated: 
ift, Whether the difeafes occupying different feats are 
not independent of each other? ad, Whether the pri¬ 
mary produces the fecondary difeafe ? 
“Jf in the courfe of a fever an abfcefs fliould form in 
one axilla, and a week afterwards an abfcefs (hould form 
in one groin ; if the eruption of the fmall-pox (hould ap¬ 
pear firft in the face, and then be extended over the whole 
body ; if a tubercle fliould form in the liver, and a month 
afterwards a vomica fliould burft in the lungs ; if a vene¬ 
real ulcer (hould form in the throat, and fix weeks after¬ 
wards a node on the tibia; we fliould fcarcely in thefe 
(and there are many fuch) cafes affert that the difeafe 
occupying the firft feat was the caufe of the difeafe occu¬ 
pying the fecond. 
“But, if one half of the body fliould be paralyzed by 
the rupture of a blood-veflei ot the brain ; if vomiting 
(hould fucceed to a blow on the head ; if difordered ref¬ 
piration fliould fucceed to the operation of a caufe of 
prefi'ure on the brain ; if atrophy fliould fucceed to difeafe 
of the mefenteric glands; if the fecretion of a gland 
fliould be fufpended during an inflammation of it ; if 
convulfions fliould fucceed the irritation of a nerve ; if 
paralyfis of the fphi abler of the bladder fliould fucceed to 
an injury of the (pine. See. —vve have no hefitationin thele 
cafes in affirming that the primary is the caufe of the fe¬ 
condary affeblion, becaufe we know that the healthy ftate 
of the properties engaged in the fecondary, acknowledge 
the regular dependent relation with thole engaged in the 
primary feat of affeblion. 
“ Again, if vomiting fliould fucceed the formation (or 
introdublion) of a calculus in the gall-duff, or to the 
pafling of a calculus along the ureter ; or if a pain in the 
fhoulder (hould fucceed an inflammation fet up in the 
liver; or if hernia humoralis fnould fucceed to an affec¬ 
tion of the urethra, perhaps produced by an injeblion ; 
or if tetanus fliould follow a punblured or lacerated 
wound ; or if pain in the breads (hould fucceed concep¬ 
tion, &c.—we have in thefe cafes no hefitation in faying, 
that the fecondary is produced by the primary change. 
“ Thefe are examples of the claffes of related difeafe. 
Difeafe of one part, or one ftate of difeafe, might produce 
another ; ift, by difturbing an habitual dependence ; and, 
2d, by the influence of an occafional caufe. The firft: is 
illuftrated above; as if an injury of the brain fliould pa¬ 
ralyze nerves whofe functions are dependent upon the 
brain, or as if refpiration fliould become laborious, or 
perhaps ceafe, by the operation of any caufe of prefl'ure 
upon the brain, &c. The fecond is illuftrated in thofe 
other examples, in which a relation is exhibited under 
circumftances of difeafe, which was not manifefted as one 
of dependence for a natural office, during health. 
“ The affeblion of a dependent feat in confequence of a 
difordered ftate of the feat from whence its functional 
properties are derived, is by no means a regular occur¬ 
rence. We know that there might be a violent pain in 
the head, a throbbing of all its vefl'els, as if the whole 
brain was violently difordered, and yet the funblion of 
refpiration, which depends upon the brain, may be but 
little or not at all interrupted ; at the fame time, a flight 
prefl'ure upon the brain (hall impair or prevent thefe de¬ 
pendent functions. The reafon is, that properties are not 
indifferently related with any caufe of diforder ; but their 
relations are precil'e ; as, properties of the brain animate 
the organs of refpiration, thefe properties related with the 
agency of prefl'ure, not related with caufes merely produc¬ 
ing pain or even inflammation ; the dependent function, 
impaired by the former, becaufe the former is related 
with the properties engaged in the dependence; not re¬ 
lated with the latter, becaufe, although they produce a 
certain affeblion of the feat of the properties which ani¬ 
mate the refpiratory organs, they do hoi; produce a change 
in the nature and relation of thefe properties, to expebl 
which would be like expebling that paralyfis of nerves 
fliould not occur from prefl'ure upon a part of the brain, 
becaufe it ftill retains fome properties of life. 
“ It has been dated that related difeafe happens in two 
ways, which may here be repeated : ift, by difturbing an 
habitual relation of the regular dependent kind ; 2d, by 
a new relation which is opened between parts not before 
connebled by intercourfe of funblion, in confequence of 
a new condition which one of them has affumed: it has 
been (fated (and examples given) that difeafe might oc¬ 
cupy a fucceffion of feats without the exiftence of any 
caufative relation between them.. It is neceffary, before 
we proceed any further, to inquire after the method of 
diftinguiffiing between difeafes which, though occurring 
in a (eries, are independent of each other, and thole 
in which the fubfequent is produced by the preceding 
difeafe. , 
“ In making this diftinblion we are liable to frequent 
error: the only grounds of the diftinblion, however, are 
as follow. Mere fucceffion, as has before been infilled, 
can never prove caufation : but it indicates caufation, 
from the analogy of fuccelfion to thofe palpable in¬ 
ftances of caufation in which the dependence of the 
effedl upon the afiigned caufe may be proved by the re- 
fult of analyfis and of fynthefis; of taking away (or 
withholding), and of combining, the caufes. Succeffion 
then, upon this ground of analogy, which has been more 
fully explained, may indicate caufation ; and yet we do 
not fuffer every inftance of fuccelfion to fugged ever fo 
faintly an inference of caufation. 
“The fucceffion of an eft'ebt to its true caufe is invari¬ 
able : from analogy in this refpebt, we infer pofitively the 
operation of a caufe in all inftances of invariable fucceffion; 
thus, day and night invariably fucceed the prefence or 
abfence of the fun. But we prefume ftill further upon 
this analogy; we infer the operation of a caufe, when the 
fucceffion of the fame confequence to the fame antecedent 
is frequent, but not invariable; thus, an ounce and a 
half 
