ON THE MESENTERIC VEINS. 
37 
a statement of Boerhaave’s* that the celebrated Cowper also, 
from minutely mjecting these parts with quicksilver, likewise 
came to the same conclusion. 
The second class of lacteals, therefore, not only take their 
immediate origin from the extreme branches of the first in the 
mesenteric glands, like the branches of two trees opposed to each 
other, but also from the extreme branches, or the transparent 
serous termination of the arteries belonging to the lymphatic 
glands ; and which last communication has also been proved by 
that which has already been so often stated relative to the second 
class of lacteals receiving red blood from the arterial, and in 
which case both sets of vessels are found to have become very 
considerably enlarged in their size, so as for the latter (the 
lacteals) to assume the same character to the real veins. 
Hence, then, it appears to me, that the second class of lacteal 
vessels, from having different origins, must, of course, be capable 
of performing a variety of different functions also; and from 
common observation, as well as from the anatomical structure of 
the parts in which these vessels are situated (for'I beg to observe 
that as well as being lacteals they are also the only lymphatic 
absorbents found in these parts), I consider that they are capable 
of performing four distinct functions ; first, that of receiving the 
chyle or new white blood from the extreme branches of the first 
class of lacteal vessels, and probably from the cells of the mesen¬ 
teric glands, in which I have some idea that the first class also 
terminate, from which \hQ second class likewise take their origin. 
Secondly, that of receiving and of returning back towards the 
centre of the circulation the transparent lymph, or white venous 
blood, from the extreme or serous branches of the arteries of the 
lymphatic glands. Thirdly, that of also taking their immediate 
origin from and of absorbing a portion of the surrounding perito¬ 
neal secretion. And, fourthly, as before stated, as those extra¬ 
ordinary cases where the function of digestion suddenly be¬ 
comes suspended, of performing a most rapid absorption of the 
adhesive substance belonging to those parts, and under such cir¬ 
cumstances these vessels becoming so much increased in size as 
to assume the same character as the real veins. 
Both the second and third of these positions will serve to 
explain that which has been so repeatedly advanced by different 
authors, respecting the character of the chyle being changed 
during the passage of this fluid through the mesenteric glands; 
for on examination it is found to have become of a more coagu- 
lable nature in the second class of lacteal vessels than it was in 
See the Lceturcs, p. 346. 
