ON THE LACTEAL AND 
€04 
The Nature and Functions of the Lacteal and Lymphatic 
Absorbents. 
After having endeavoured to give a short outline of the various 
opinions which have, from time to time, been advanced with re¬ 
gard to the nature and functions of those vessels commonly called 
lacteal and lymphatic absorbents, I shall, in the next place, en¬ 
deavour to point out what I consider to be their real nature and 
use. 
It has already been stated, that the anatomists who first dis¬ 
covered the lacteal and lymphatic vessels conceived them to be 
only a set of serous veins, taking their immediate origin from, or 
being a continuation of the minutest terminations of the serous 
arteries; that the lacteals arose also from the inner surface of 
the intestines : and that the use of these two orders of vessels 
was, for the purpose of absorbing the chyle, and also to receive 
the transparent, and refuse the red or coarser part of the blood # ; 
* “ Every artery in the human body,” says Boerhaave, “ is larger than 
any branch that it emits, as we are assured by our senses, so long as the eye 
or microscope can trace them; and it is, doubtless, the same in those ex¬ 
ceeding small arteries, whose minuteness and pellueidity conceal them from 
the eye, both naked or armed. But the particles of the contained fluid will 
be always in proportion to the diameter of their canals, so that if a small 
artery, admitting only single red globules, is ramified, all its branches will 
be less than those globules, which they therefore will not receive, but they 
M ill admit those parts of the blood which are less than the red globules, or 
which are proportionable to their diameters, while the larger red particles 
m ill pass on into the red or sanguiferous vein. But the next lesser parts of 
the blood, to the red globules, are the yellow serous ones; and therefore 
the lateral branches of the smallest sanguiferous arteries will be filled with 
serous globules, and constitute a second order of vessels, viz. serous 
ones. That there are such serous vessels is proved by the microscope, in¬ 
jections, and the natural eye in an ophthalmia, where the red blood is forced 
into the serous vessels of the sclerotica. But these serous arteries again 
divide into smaller branches of less diameters than their yellow r serous 
globules, and these branches will therefore be filled with the lymphatic 
globules which are the next less in size to the yellow serous ones, and 
constitute a set of arteries of the third order, termed lymphatic arteries, 
such as furnish the aqueous humours of the eyes, which humours arc ab¬ 
sorbed or returned again to the blood by serous or lymphatic veins. Hence, 
then, the sanguiferous arteries will carry all the parts of the blood, the se¬ 
rous arteries will convey all but the red globules, and the lymphatics all 
but the red and yellow globules, &c .; and thus probably is the succession 
of vessels and humours continued, till the ultimate or last series of the 
smallest vessels convey only the most subfile juices of the body.”— Pro¬ 
fessor Boerhaave’s Academical Lectures on the Theory and Practice of Phy¬ 
sic. Yol. ii, p. 217 , 1743 . 
I have introduced these remarks of Professor Boerhaave’s, not because I 
agree with him as regards the red and yellow globules , fyc. contained in the 
circulatory fluids, but because I accord with him as regards the ramifica¬ 
tion and distribution of the sanguiferous and seriferous arteries, veins, &c. 
