838 
PATHOLOGY. 
Praft. iii. 254.—In the thymus gland; A3. Med. Bcrol. 
vol. i. p. 28.—In the thyroid ; Con/uli de Lapid.—In the 
parotid; Plater Obf. lib. iii. 707.—In the deltoid muf- 
cle ; Ruffe, in Blegny Zodiac, 1680.—In the trachea, 
contracting its paffage ; Kirkring, Obf. 27.—In the dura 
mater; Rnillie, Fafc. X. Pi. 4. 
2. Ofthexia implexa: offific matter depofited in con¬ 
centric layers in the tunics of veflels or membranes, ren¬ 
dering them rigid and unimpreffible. Three varieties. 
a. I. aortae; offification of the aorta.—With a confi- 
derable portion of the right ventricle and right auricle of 
the heart. Baillie, Fafc. V. PI. 2. Valves offified without 
palpitation or dyfpr.cea. Morgagni de Sed. et Cauf. Ep. 
xxiii.n.—Defending trunk wholly offified. Genga Anat. 
chirurg. Buckner Mifcel. 1727.—Afcending and defend¬ 
ing trunks wholly odified, compelling to an ereft pofition. 
Gvattani de Aneurifm. 
13 . I. tnembranea ; offification of membranous or con- 
nefting parts.—Of the pleura ; Baillie, Fafc. II. PI. 3.— 
General offification of tendons, membranes, cartilages, 
and ligaments. Pccklin, lib. ii. Obf. 40. 
y. I. complicata; offification of different parts fimulta- 
neoufly; as of the thoracic duft, ileum, and other abdo¬ 
minal organs. Phil. Tranf. 1780. 
Order II. CatqjTCa, [from v.a.'ro], within.] Diforders 
affefting Internal Surfaces. Pravity of the fluids, or 
emunftories tha/open into the internal furfaces of or¬ 
gans. There are three genera. . 
Genus I. Hydrops, [from v<iuo, water,] Dropfy. Ge¬ 
neric characters—Pale, indolent, and inelaflic, diflention 
of the body or its members from accumulation of a wa¬ 
tery fluid in natural cavities. 
It has been afeertained by phyfiologifls, that, in the 
healthy condition, a ferous or watery fluid is conftantly 
poured out, or exhaled, from what are termed the exha- 
lent extremities of the arteries, into every cavity and in- 
rerftice in the body, by which the parts are conllantly 
thoiftened, and their adhefion, or painful attrition, is pre¬ 
vented. But upon the furfaces of the fame cavities and 
interftices the mouths of another fet of veflels, the ab- 
forbents or lymphatics, open, and take up or abforb this 
eft'ufed fluid before it has remained long, or been accu¬ 
mulated in thofe fpaces, and carry it back into the cir¬ 
culating blood, through the thoracic duft, or general 
trunk of the abforbents. From this view of the animal 
economy, it at firfb feemed obvious that a perfeft balance 
between thefe oppofite funftions of exhalation and abforp- 
tion mil ft exift, in order to maintain the health of the 
fyfiem ; and that a dropfical accumulation muft be the 
confequence of the lofs of fuch balance, and mull; be oc- 
cafioned in one or other of the two following ways : 1. 
If the quantity of fluid poured out into any fpace be 
greater than theabforbent veflels can at the fame time take 
up, it muft neceffarily accumulate in fuch parts; or, 2. 
Although the quantity poured out be not greater than 
ufual, yet, if the abforption be any-how interrupted or di- 
miniflied, an unufual accumulation will from this caufe 
alfo enfue. Dropfy was in general therefore imputed to 
an increafed exhalation or a diminifhed abforption, in 
the cavities in which it occurs. It will be found, how- 
ever, upon an inveftigation of the various caufes which 
are capable of producing thefe morbid conditions, that 
the exhalent veflels are commonly in fault, and that a 
plethoric flate of the blood-veflels of the dropfical part is 
the next link in the chain of caufes. This plethoric con¬ 
dition may or may not be accompanied w’ith inflammation 
of the red veflels ; but, if fuch aftion do exift, the effufion 
of ferum will be more rapid, and will be of a tenacious 
and gelatinous, or otlierwife thickened, confiftence or 
Iftrufture. 
Of all other parts of the body, the ferous-membranes 
are moft fubjeft to effufions of water. Thus in the peri¬ 
toneum we meet with afeites, in the pleura with hydro- 
thorax, and in the flgmoidal capfules with fimilar effufions. 
They are, however, by no means confined to thefe parts. 
The fitfin, irritated by ablifter or by fpecific difeafe, gives 
examples of aqueous effufion under various appearances 
of veiicles, blebs, &c. The efi'ufed fluid exhibits differ¬ 
ent appearances; being fometimes aperfeftly aqueous 
fecretion, like the natural ferum of the blood, and at 
other times quite different. Moreover, the fame veflels 
which, under a trifling excitation, fecrete undue quanti¬ 
ties of ferum, when more morbidly ftimulated pour forth 
pus and coagulating lymph. Every thing that throws 
an inordinate flow of blood to the ferous niembranes 
may occafion dropfy ; and in faft peritonitis,, pleuritis, 
afeites, and hydrothorax, may often be traced to the 
fame caufes. 
Of all other caufes of afeites, an accumulation of 
blood in the peritoneal veflels h the moft frequfent. Thus 
we find, that, if the liver be difeafed in fuch a manner as 
to obftruft the blood which flows from the inteftines 
through the vena portae to the heart, the afeites is an 
almoft invariable confequence. Now in the cafe of tu¬ 
bercles or hydatids in the liver, the impediment being of 
courfe gradual in its formation, we do not often find 
inflammatory fymptoms accompanying the difeafe; but, 
if cold be taken, we frequently find that inflammation 
dees come on. Again ; obftruftion to the flow of blood 
through the lungs, as in afthma, brings on various forms 
of dropfy, but efpecinlly hydrothorax. Moreover the 
prefence of the gravid uterus, or of any tumour in the 
abdomen, by preffing on the great veflels which retain 
the blood from the lower extremities, give rife to cede- 
matous fwellings under the integuments. Dropfy‘is alfo 
a fequel of fevers, efpecially of Rofalia. Befides in¬ 
creafed aftion of the fecernent veflels, dropfy feems to 
owe its origin to a preponderance of ferum in the blood ; 
and in this cafe paffive plethora is generally found in a 
remarkable degree. General plethora alfo brings on 
dropfy ; and we find it a very common fequel of repreffed 
difeharges, as piles, ulcers, or the like. 
Of the mode in which abforption may be difttirbed or 
accelerated we have before fpoken at large in another part 
of this article. The connexion of diminifhed abforp¬ 
tion with dropfical effufion is obvious enough, either as 
a caufe or an effeft. Diminution in the quantity of urine 
is always met with in dropfy; and a diftinftion has been 
made by Dr. Blackall between inflammatory and chronic 
dropfy, according to the degree of coagulability of this 
fluid. In inflammatory dropfy this author ftates that the 
urine is eafily coagulable on the application of heat; while 
in chronic dropfy this coagulation is abfent altogether, 
or at leaft is very trifling in degree. This diftinftion has 
been contradifted; and we are enabled to ftate, from 
fome experiments of our own, that it is not tenable. By 
this ftatement we do not mean to detraft from the merits 
of Dr. Blackall, who muft be acknowledged to have done 
much to improve the treatment of dropfy. 
The fymptoms vary as this difeafe affefts different parts, 
as appears from the following details of the fpecies. 
1. Hydrops cellularis : cold and diffufive intumefcence 
of the fkin, pitting beneath the preffure of the finger. 
Three varieties. 
a. Totius corporis,-anafarca, or general dropfy: ex¬ 
tending through the cellular membrane of the whole 
body. 
( 3 . Artuum, edema, limited to the cellular membrane 
of the limbs ; chiefly of the feet and ancles, and moftly 
appearing in the evening. 
y. Dyfpnoica ; edematous fwelling of the feet; ftiff- 
nefs and numbnefs of the joints ; the fwelling rapidly 
afcending to the belly, with fevere and, moftly, fatal 
dyfpncea. This very fevere and Angular variety is taken 
from Mr. W. Hunter’s Effay, publifhedat Bengal, folio, 
1804. The difeafe appeared with great frequency among 
the Lafcars in the Company’s fervicein 1801. Its attack 
was fudden ; and its courfe fo rapid, that it frequently 
killed the patient in two days. Mr. Hunter aferibes it 
to 
