33 
P A T II O L O G Y. 
to which we muil allow the merit of ingenuity, became 
generally received. Mechanical principles were applied 
to every function of the body: not only the motion of 
the blood, but the compofition of that fluid, and the va¬ 
rious and elaborate precedes of nutrition, fecretion, &c. 
were referred to the fame laws. Thisabfurd application 
of mathematical knowledge to vital phenomena, led thefe 
philofophers into a labyrinth of error aftonifhing to com¬ 
mon fenfe. For inftance, while one author calculated 
the contractile power of the femoral artery at upwards of 
1000 pounds, he overlooked the very obvious circum- 
ftance, that the pulfation of that vedel may be immedi¬ 
ately fufpended by the ufe of a tourniquet which fcarcely 
exerts the predure of a few pounds. Indeed, the con¬ 
tradictory refults arrived at by thefe experimenters (howed 
the abfurdity of their experiments. Thus, Borelli af- 
ferted that the contraction of the heart was equal to a 
refiftance of 180,000 pounds ; Keil, that it was equal to 
five, or, at molt, eight ounces. Hecquet calculated the 
digeltive (or, ac,cording to him, triturative) powers-of 
the Itomach, in conjunction with the abdominal mufcles, 
to be equal to 261,000 pounds ; Altruc ftated the amount 
of that power at four pounds three ounces. 
Yet was this mode of inveftigating the fcience of life 
by no means ufelefs ; for, by teaching pathologifts to re¬ 
fort frequently to experiment in proof of their afi'ertions, 
it deftroyed the attachment to fanciful and gratuitous 
hypothefis which had fo long prevailed : it directed their 
attention to parts and aCtions of the animal economy 
which the humoral phyficians had paded over unnoticed 
and undeferibed; and, what was of ftill more impor¬ 
tance, it induced correCt and analytical habits of reafon- 
ing. Accordingly, we find, during the 17th century, 
which may be confidered as the period at which the me¬ 
chanical philofophers principally flourilhed, difeoveries 
which have flood the teft of time, and theories, concern¬ 
ing the correCtnefs of which we are ftill earneftly em¬ 
ployed in difeuflion. Phyfiology and the minute parts 
of anatomy were inveftigated with the grandeft refults; 
the circulatory fyftem was gradually and fuccefsfully il- 
luftrated by many diftinguifhed phyfiologifts. Excellent 
deferiptions of the ItruCture and relative pofition of the 
heart were given by Steno and Lower. The microfcopi- 
cai experiments of Leeuwenhoek and others ferved to 
eftablifh the important faCl of the continuation of arte¬ 
ries and veins with each other. Ruyfch likewife, by the 
great degree of nicety in the ufe of injections to w hich 
he attained, was enabled to throw much light on this fub- 
jeCl. Some important parts of the arterial fyftem were 
difeovered by VieulTens. The necefiity of the abforption 
.of oxygen gas through the lungs was firft inculcated by 
Mayow. Malpighi improved the knowledge of the ftruc- 
ture of thofe organs. 
The mechanical part of refpiration, the compound ac¬ 
tions of the mufcles, See. were beautifully demonftrated 
by Borelli; and Kepler applied mechanical principles to 
the explanation of the functions of the eye in a manner 
the moft clear and fatisfaCtory. He firft pointed out the 
true ufe of the cryftalline lens, and fhowed how the 
images of external objects are formed, in an inverted po¬ 
fition, on the retina. A public experiment with the eye 
of an ox, which was made at Rome, in 1625, by the Je- 
fuit Scheiner, fully confirmed Kepler’s theory: but af¬ 
terwards Mariotte, having found that the images of ob¬ 
jects difappeared when they fell on the fpot where the 
optic nerve enters the eye, called in queftion the fenfibi- 
lity of the retina, and maintained that the choroid coat 
was better calculated to receive and rranfmit the percep¬ 
tions of fight; and a controverfy arofe concerning the 
aCtual feat of vifion, which was carried on, with great 
eagernefs, by Pecquet, Perrault, and St. Yves, and 
which had the effeCt of eliciting many valuable obferva- 
tions. The Newtonian difeoveries, refpeCting the pro¬ 
perties of light, contributed ftill more to the accurate 
analyfis of the functions of the eye; and the treatifes of 
Vol. XIX. No. 1285. 
Du Petit, Porterfield, and Zinn, which followed foon 
after, have left little for their fuccefiors to accomplifh. 
The lymphatic fyftem was likewife brought into notice 
during this century. To Cafpar Afellius is due the 
merit of having taken the firft ftep in the inveftigation of 
this important part of the animal frame. While diffeCl- 
ing a dog, for the purpofe of demonftrating the recur¬ 
rent nerves, the appearance of a milk-like fluid iffuing 
from fome fmall white veflels arrefted his attention. 
Examining them more minutely, he traced them to the 
villous coat of the inteftines; and repeated difleClions 
informed him, that thefe veflels -were only obfervable in 
the animal which had lately fed. Hence he concluded 
thefe to be the vafa chylifera. He confefled, however, 
that thefe veflels had been mentioned by ancient au¬ 
thors, though deferibed in a very imperfeCl manner; 
but he juftly claimed the honour of having firft pointed 
out their ufe. Afellius, however, entertained erroneous 
ideas as to the termination of the ladeals : he fup- 
pofed that they united together in the pancreas, and 
pafled from that gland into the liver. This error was 
corroded by the rel’earches of Pugent, who, obferving on 
one occafion a milky fluid in the vena cava of a dog, traced 
carefully the progrefs of that veflel, and difeovered the 
thoracic duCt. This difeovery was difputed however 
with much acrimony; and the character of Harvey was 
tarniflied by the circumftance, that he flood forth among 
the moft illiberal of its opponents. The abforbents of 
the large inteftines were difeovered by Olaus Rudbeck 
in the year 1651 ; he likewife refuted the received opi¬ 
nion, that the liver poflefled laCteals, and, by their 
means, aflimilating powers : he fhowed that the only ab- 
forbent veflels exifting which could have led to this 
error, were the lymphatics of the hepatic glands. The 
glandular fyftem in general was afterwards more fully 
illuftrated by the writings of Gliifon and Wharton, 
the experiments of Lower, Drelincourt, Lifter, and 
Mufgrave; and the anatomical refearches of Nuck, 
Pacchioni, and Duverney. 
Nor were the more abftrufe and difficult queftions of 
phyfiology negleCted by the philofophers of this age. 
With much talent Willis fupported the hypothefis of a 
nervous fluid, the vehicle of animal fpirits ; and, when 
deficient or exceffive, the caufe of diforder; and he feems 
in fome refpeCts to have anticipated the fpeculations of 
Spurzheim and Gall, in referring to particular parts of 
the brain peculiar mental faculties. The errors of this 
author on the former fubjeCl were pointed out by Mal¬ 
pighi, who moreover inveftigated the cerebral ftruClure 
with great minutenefs, particularly in reference to tire 
exiftenceof fibres in the cortical fubftance. Here too the 
injections of Ruyfch and the microfcopical experiments 
of Leeuwenhoek were ufefully employed to fliow the vaf- 
cularity of the brain. Many improved deferiptions were 
furniflied by Cafferius, Duverney, Riverius, Vieuflens, 
and others, of the ftruClure of the ear. The tunica 
arachnoides was deferibed by Swammerdam and Blaes. 
Many interefting experiments were made on the genera¬ 
tion of animals ; among which the moft famous, though 
certainly not the moft ufeful, was that of Leeuwenhoek 
on the animalculae of the feminal fluid. See our article 
Animalcule, vol. i. p. 727. 
To the “ triumviate,” as they have been called, Stahl, 
Hoffman, and Boerhaave, pathology and therapeutics 
are indebted for many important illuftrations. The firft 
of thefe phyficians has rendered himfelf famous by the in¬ 
troduction of an hypothefis, which, with various altera¬ 
tions, has maintained its ground until the prefent day. 
We allude to the exiltence of an immaterial principle, or 
effence, as producing the phenomena of life. The particu¬ 
lar tenets, however, on which this theory was founded, 
had been promulgated before the time of Stahl: Rene 
des Cartes had taught his followers to conlider matter as 
purely paflive, and to refer all the changes to which it is 
fubjeCted to a fpiritual caufe: the union of body and 
K fpirit 
