206 
Syn. Absorbent system.)—The lymphatic sys- 
tem is com ad in the first place, of the 
vessels which collect and convey the lymph 
from all parts of the body and the chyle from 
the intestines, and ultimately deposit them in 
the veins. Secondly, of the small fleshy bo- 
dies called conglobate, lymphatic, or absorbent 
glands, which are found connected with this 
system of vessels in various parts of their 
course. 
The lymphatic system is confined to the 
class Vertebrata. It is the least complicated 
in Fishes, and consists in them simply of pel- 
lucid valveless vessels. In Reptiles, also, it 
is composed of these vessels only, but which 
are armed with more or less perfect valves. In 
the two higher orders of Vertebrata, Birds and 
Mammalia, to the vessels containing very nu- 
merous and perfect valves, the conglobate 
glands are superadded : in all, however, the ter- 
mination of the system is in the veins, and its 
origin and general arrangements are probably 
in all essentially the same. 
The different parts of the lymphatic system 
had escaped the notice of anatomists until the 
middle of the sixteenth century, and the entire 
system was not discovered till the middle of 
the seventeenth. I must here except the lym- 
“soe glands, which from their large size must 
ave been observed by the earliest anatomists, 
and we accordingly find them alluded to by 
Hippocrates, who classed them with the other 
glandular organs. 
The first isolated discovery in the vascular 
part of this system was made by Eustachius in 
1563, who saw and described accurately the 
thoracic duct in a horse. He called it the 
vena alba thoracis, and traced it downwards 
from the left subclavian vein to the lumbar ver- 
tebre, where he noticed the dilatation now 
called the receptaculum chyli ; he however had 
no conception that it formed the trunk of a se- 
parate system of vessels, but conceived it to be 
a vein of apeculiar kind. Fifty-nine years af- 
terwards, in the year 1622, Asellius was fortu- 
nate enough to discover the lacteal vessels on 
the mesentery of a dog; and although on the 
following day he was much disappointed in not 
being able to see them in another dog in- 
spected for the purpose, by continuing his re- 
searches he soon convinced himself of their ex- 
istence in most animals. He also attributed to 
them their proper function, having remarked 
that whenever there was chyle in the intestines, 
these vessels also contained a white fluid, and 
could then only be seen. He failed, however, 
to connect the vena alba thoracis, the discovery 
of Eustachius, which had probably been for- 
gotten, with his own, and mistaking the lym- 
phatics of the under surface of the liver for the 
continuation of his vessels, was led into the 
error of supposing them to terminate in the 
liver. Asellius, who died in 1626, had not 
seen the lacteals in man, but inferred and as- 
serted their existence. According to Haller, 
Veslingius was the first who saw these vessels 
in the human subject, in the year 1634; but 
Breschet informs us, in his Systéme Lympha- 
tique, page 4, that, “en 1628, les lympha- 
LYMPHATIC AND LACTEAL SYSTEM. 
s pour la p - 
Sen 
tiques du mésenttre furent aperou 
mitre fois chez homme. Peirese, ur 
d’Aix, informé par Gassendi de la découvert 
qu’ avait faite Aselli, distribua plusieurs exem 
plaires de l’ouvrage de ce proffesseur aux n 
decins de sa connoissance, et leur abandonna 
criminel condamné a mort, pour verifier le fi 
sur son cadavre. On fit bien ( 
homme avant de le conduire au supplice, 
une heure et demie aprés sa mort, louvertu 
du bas ventre montra le mésent®re tout cor 
vert de vaisseaux lactés pleins de chyle.” 
The thoracic duct was rediscovered in t 
year 1649, by Pecquet, who published ad 
scription of it in 1651. Haller ascribes 
discovery to Veslingius: “Idem Veslingiu: 
nisi plurimum fallor, primus post Eustachiom 
contra omnes coetaneos, rectius anno 1649 
vidit vas lacteum grande, in pectus adscender 
cum reliqui incisores, partim ab Asellio pr 
suasi, et partim a lymphaticis vasis hepatis 
ducti, chyliferos ductus ad hepar ducerent.” — 
It now became evident that the thoracie di 
was the trunk of the vasa lactea, and that th 
chyle was not conveyed to the liver, as : 
supposed, but was poured into the venous sy 
tem at the union of the subclavian and interr 
jugular veins of the left side. The lymphat 
of the under surface of the liver were soon aft 
shewn by Glisson and Veslingius to have t 
valves so arranged as to convey their cont 
from, and not to this organ. 
In the two or three following years the 
of the lymphatic system was discovered 
Rudbeck in Sweden, by Bartholin in Den 
mark, and by Jolyffe in this country ; nor wa 
it long before the function of absorption wi 
ascribed to it by Glisson, in 1654, and b 
Hoffmann. Since this period, we have been it 
debted for various details of the arrangement © 
this system of vessels in man and other Mam 
malia, in Birds, in Reptiles, and Fishes, 
numerous investigators, Nuck, Ruysch, A 
nus, Meckel, Hunter, Monro, Hewson, Cruiel 
shank, Semmerring, Mascagni ; and in the pre 
sent day to Fohmanu, Lauth, Lippi, 
Panizza, and other continental anatomists. 
The lymphatic vessels in the human sub ec 
are exceedingly delicate and transparent tub 
numerous but small, existing in most if me 
in every part of the organism, cro 
with valves, and terminating, after pass 
through the glandular bodies, in two prine 
pal trunks, through which the contents of th 
whole system are emptied into the circulatii 
venous blood at two corresponding Sie 
far distant from the heart, viz. at or close te 
angles of union between the subclavian am 
internal jugular veins. The two trunks of tl 
lymphatic system are by no means 
trical. That which enters the veins on the I 
side measures as much as sixteen or eightei 
inches in length in the adult human sub 
It commences in the abdominal cavity by 
a slightly marked dilatation, the recepta em 
chyli, into which the chyliferous vessels pour their 
contents ; it then passes through the thorax to 
reach its termination in the neck. This trunk 
is usually termed the thoracic duct ; it may 
Loe 
