most part mild and innocent; as
water, chyle, and the natural mucus: or they take their properties from the
materials previously absorbed, as in the coloured or vinous urine, or that
scented with asparagus, described before.

2. Whenever the secretion of any fluid is increased, there is at the same
time an increased heat in the part; for the secreted fluid, as the bile,
did not previously exist in the mass of blood, but a new combination is
produced in the gland. Now as solutions are attended with cold, so
combinations are attended with heat; and it is probable the sum of the heat
given out by all the secreted fluids of animal bodies may be the cause of
their general heat above that of the atmosphere.

Hence the fluids derived from increased secretions are readily
distinguished from those originating from the retrograde motions of the
lymphatics: thus an increase of heat either in the diseased parts, or
diffused over the whole body, is perceptible, when copious bilious stools
are consequent to an inflamed liver; or a copious mucous salivation from
the inflammatory angina.

3. When any secreted fluid is produced in an unusual quantity, and at the
same time the power of absorption is increased in equal proportion, not
only the heat of the gland becomes more intense, but the secreted fluid
becomes thicker and milder, its thinner and saline parts being re-absorbed:
and these are distinguishable both by their greater consistence, and by
their heat, from the fluids, which are effused by the retrograde motions of
the lymphatics; as is observable towards the termination of gonorrhoea,
catarrh, chincough, and in those ulcers, which are said to abound with
laudable pus.

4. When chyle is observed in stools, or among the materials ejected by
vomit, we may be confident it must have been brought thither by the
retrograde motions of the lacteals; for chyle does not previously exist
amid the contents of the intestines, but is made in the very mouths of the
lacteals, as was before explained.

5. When chyle, milk, or other extraneous fluids are found in the urinary
bladder, or in any other excretory receptacle of a gland; no one can for a
moment believe, that these have been collected from the mass of blood by a
morbid secretion, as it contradicts all analogy.

---- Aurea durae
Mala ferant quercus? Narcisco floreat alnus?
Pinguia corticibus sudent electra myricae?--VIRGIL.

IX. _Retrograde Motions of Vegeta