ON THE LACTEAL AND LYMPHATIC VESSELS. 
435 
the body, it be requisite for the second class of lacteal vessels to 
assu?ne the same character as the red veins , and absorb at the same 
time, these red veins not only are capable of removing or absorb¬ 
ing, but do remove and absorb a much larger portion of the body 
than either the lacteals or lymphatics; the latter of which, ac¬ 
cording to the theory of Mr. J. Hunter, have usually been con¬ 
sidered as the sole absorbents of the body. 
On the Discovery of the Lacteal and Lymphatic Vessels. 
We are told that Harvey discovered the circulation of the 
blood in the year 1616, although he did not publish his disco¬ 
very until 1628. In the previous year (1627), Aselius, Profes¬ 
sor of Anatomy at Pavia, discovered the lacteal vessels in the 
mesenteiy of brutes, and which had already been noticed in the 
writings of Hippocrates, Galen, &c., but without their attempt¬ 
ing to give any description of the real nature or use of these ves¬ 
sels; consequently this subject remained in a state of darkness 
and doubt until the time of Aselius, who, on opening the abdo¬ 
men of a dog, to observe the motions of the diaphragm, saw a 
number of white filaments on the mesentery, which he at first 
mistook for nerves, but on puncturing one of them, he found it 
to discharge a white milk-like fluid. He immediately and eagerly 
claimed the discovery of a new set of vessels, a fourth kind; 
for, prior to this time, the nerves were also considered as a sys¬ 
tem of vessels. 
Aselius not only discovered the lacteal vessels, but also inves¬ 
tigated and announced their peculiar office ; namely, the absorp¬ 
tion of chyle from the intestinal canal, and the conveyance of it 
into the blood. 
For some time after the alleged discovery of these vessels, 
they w r ere considered as fictitious by the majority of anatomists; 
and the doctrine which had been taught by Hippocrates, Galen, 
and other writers, was still believed, viz. that the mesenteric veins 
absorbed the chyle from the intestines, and conveyed it to the 
liver, where it was converted into red blood. Even for some 
time after the discovery of the lacteals in the human subject, in 
1634, by Veslingius, and who attempted to give a drawing of 
them, a portion of the old system was retained, and it was 
affirmed, that the lacteals conveyed the fluid which they absorbed 
from the intestines into the liver, and that the chyle was there 
converted into red blood. In the year 1651, however, Pecquet, 
in dissecting a dog in order to observe the lacteals, discovered 
the lymphatics, and traced them to the thoracic duct: this, 
in point of fact, had been observed in the horse, by Eustachius, 
a human anatomist, in the year 1563, but, from his not having 
