ANATOMY, % s 
ure fmall orifices adapted to imbibe them : the only 
queffion is, what the veflels, are to which thefe orifices 
'belong, whether to the lymphatic ffyftem, or to the com¬ 
mon veins ? 
That the common veins did the office of abforbing both 
the chyle and the lymph, was the opinion of anatomifts 
before Afellius difcovered the ladleals; but after his time 
•few doubts were entertained of the ladteals abforbing at 
leafi: a part of that fluid. Yet many anatomifts have been 
do tenacious of the old opinion, as (till to believe that the 
veins partly performed that office, or abforbed fome’of the 
chyle, and carried it to the liver. However, upon taking 
a review of all the arguments itr favour of the doctrine that 
■the common veins are the inftruments of abforption, that 
•doftrine appears to have no other fupport than refpedt for 
■the authority of our predeceffcrs. And, although this idea 
was formerly fo generally received, yet there were even 
then fome phyfiologifts who reafoned better on the fub- 
jedt ; and amongft the firfi: of thefe was GlifFon, who at¬ 
tributes to thofe velfels the office of carrying'back to the 
blood-velfels the lymph which had lubricated the cavities 
■of the body. M. Noguez, likewife, fpeaks of abforption 
by the lymphatics. Hambergerus alfo feetns to have had 
this idea of their office: and Frederic Hoffman has ex- 
-preffed the dodhine of the lymphatics being abforbents 
very completely, in his Medic. Ration. Syftem. lib. i. 
ffedt. 2. cap..3. This opinion has, alfo been adopted, and 
fupported with additional arguments, by doctors Hunter 
■and Monro ; who, bolides lliewing the fallacy of the ex¬ 
periments brought in favour of the common veins doing 
the office of abforption, have advanced the following ar¬ 
guments to prove that the lymphatics perform it. Firlt, 
Their great analogy with the ladteals, with which they 
agree in their coats, in their valves, in their manner of 
•ramifying, in their paffage through the lymphatic or con¬ 
globate glands, and in their termination in the thoracic 
dudt, and in fhort in every circumflance with regard to 
their ftrudture. Secondly, The paffage of the venereal, 
variolous, and other, poifons, into the conftitution.; thele 
-poifons firfi: making an ulcer, and then being abforbed 
along with the matter of the ulcer and infecting the whole 
body. That in fuch cafes they are not abforbed by the 
common veins, but by the lymphatics, appears from their 
inflaming thefe lymphatics in their cotirfe, and by their 
generally inflaming.a conglobate gland before they enter, 
the fvftem ; a ftrong argument in favour of their being ta¬ 
ken up by the lymphatic veflels which pafs through thefe 
glands in their Way to the thoracic duel. Such, then, 
deems to be the purpofe for which the lymphatic veflels 
were provided; that is, to do the office of abforption ; an 
office of the greateft importance to the animal: no wonder, 
therefore, that there fhould be a fyftem fet apart for per¬ 
forming it, and not only in man and quadrupeds, but alfo 
in birds, fifh, amphibious animals, and perhaps even in 
jnfedts of the minuteft kind. 
OF THE NERVES. 
THERE are forty pai-r of nerves in all, of which ten 
come from the encephalon, and the other thirty have their 
■origin from the fpinal marrow. Of the ten pair which 
come from the encephalon, the firfi: is the olfaElory, which 
long had the name of the mamillary procejfes of the brain; 
becaufe in cows and lheep, which were moil commonly 
diffedted by the ancients, the anterior ventricles of the 
brain are extended forwards upon thefe nerves, and ad¬ 
here fo firmly to them, that they feem to make the upper 
fide of the nerves. Each of them being large where it 
begins to be ftretched out, and gradually becoming fmaller 
as it approaches the cribriform bone, was imagined to re- 
femble a nipple. The tender ftrudture and fudden ex- 
panfion of thefe nerves on fuch a large furface, render it 
impoffible to trace them far ; which has made fome au¬ 
thors deny them to be nerves: but, when we break the 
circumference of the cribriform lamella, and then gently 
raife it, we may fee the diffribution of the nerves fome 
Vojl. I. No, 40, 
way on the melnbrane of the nofe, where they form a 
beautiful net-work. 
The fccond pair of nerves are the optic , which make a 
large curve outwards, and then runobliquely inwards and 
forwards, till they unite at the fore-part of the fella tur¬ 
cica ; they then divide, and each runs obliquely forwards 
and outwards to go out at its proper hole in the fphenoid 
bone, accompanied with the ocular artery, to be extended, 
to the globe of the eye, within which eacii is expanded 
into a very fine cup-like web, that lines all the infide of 
the eye, to within a little difcance of the edge of the cry- 
ftalline lens, and is universally known by the name of re¬ 
tina. The retina of a recent eye, without any preparation, 
appears-a very fine web, confiding of fibrils fo extremely 
fmall, that each expanded optic nerve cannot exceed in 
diameter the 32,400th part of a hair! There are alfo fome 
blood-veflels arifing from its centre to be diflributed on it-: 
and if thefe veflels lofe their tone, and remain preternatu- 
rally diftended, no objedt affedts our retina, though the 
eye-externally appears found; or this may be one cr.ufie of 
an amaurofis or gutta ferena. From a partial diffention 
of thefe veflels, or paralyfis of a part of the retina, the 
central part, or the circumference, or any other part, of 
objedts-may be loff to one or both eyes. 
The third pair rife from the anterior part of the-pro- 
ceflus annularis; and, piercing the dura mater a little be¬ 
fore and to a fide of the ends of the pofterior clinoid -pro- 
cels of the fphenoid bene, run along the receptacula, or 
cavernous finufes, at the fide of the ephippium, to get 
out at the foramina lacera: after which each of them di¬ 
vides into branches ; one of which, after forming a little 
ganglion, is diflributed to the globe of the eye ; the others 
are lent to the mufculus redtus of the palpebra, and to the 
attolens, addudtor, deprimens, and obliquus minor, muf- 
cles of the eye-ball. Thefe mufcles being principal inftru- 
ments in the motions of the eye-lid and eye-ball, this 
nerve has the name of motor oculi. The diflenfion of a 
conliderable branch of the carotid, which paffes over this 
nerv.e near its origin on each fide, may poflibly-be the rea- 
fon of the heavinels in the eye-lids and eyes, after drink¬ 
ing hard, or eating much. 
The fourth pair, which are the fmalleft nerves of any, 
derive their origin from the back-part of the bafe of the 
tefles ; and then making a long courfe on the fide of the 
annular protuberance, enter the dura mater a little farther 
back than the third pair, to run alfo along the recepta¬ 
cula, to pafs.out at the foramina lacera, and to be entirely 
(pent on the mufeuli trochleares, or fuperior oblique muf¬ 
cles of the eyes. Thefe mufcles being employed in per¬ 
forming the rotatory motions, and the advancement of the 
eye-bails forward, by which feveral of our paflions are 
exprelfed, the nerves that ferve them have the name of 
patJietici. 
The fifth pair are large nerves, riling from the annular 
proceffes, and then finking clofe by the receptacula at the 
fides of the fella turcica, each becomes in appearance 
thicker, forms a diflindt ganglion, and goes out of the 
Ik nil in three great branches. The firfi branch is the 
ophthalmic ; which runs through the foramen laeerum to 
the orbit, having in its paffage thither a connedtion with 
the fixth pair. It is afterwards diflributed to the ball of 
the eye with the third ; and to the nofe with the olfadtory. 
The fmall fibres which this firlt branch of the fifth and 
third pair of nerves fend to the eye-ball, being fituated on 
the optic nerve, and, after piercing the fclerotic coat, 
running along the choroid coat on the outfide of the retina 
in their courfe to the uvea or iris, may be a caule of the 
fympathy between the optic nerve and the uvea; by which 
we more readily acquire the habit of contradting the iris, 
and thereby leffen the pupil, when too ftrong a light is 
excluded; and, on the contrary, enlarge the pupil when 
the light is too faint. This, with the fympathy which 
muff arife from fome of the nerves of the membrane of the 
noftrils being derived from this firft branch of the fifth 
pair of nerves, may alfo be the caufe, why an irritation 
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