«14 OF THE MOST REMARKABLE
It is, however, to be obferved, that an inflammation of the exter¬
nal membrane of the liver or lungs is attended with confiderable
pain, and a hard pulfe, as in a pleurify.
3. A too foft pulfe is owing either to a laxity of the whole veflels,
and particularly of the capillary arteries, or to a thinnefs or watery
Rate of the blood, which paffes into the veins and fecretory veflels
;fo eafily, that it can exert little of its force in dilating the arteries.
A foft pulfe is more common than a hard one, in thofe patients
who are fubjedl to nervous or hyfteric complaints ; becaufe too
thin blood and a laxity of the vafcular fyftem are more common
in fuch, than denfe blood and a too great tenfion or fpafmodic con«
traélion of the arteries, which occafion a hard pulfe.
4. A pulfe quicker than natural muft be owing to one or more
of the following caufes, viz. an increafe of the flimulating quality
of the blood, its quicker return to the heart, or a greater degree of
fenfibility, and confequently a greater aptitude for motion in the
heart.
(a) The flimulating quality of the blood is increafed, by its be¬
coming too denfe or fizy, by external heat, by frefh chyle, fuch e-
fpecially as is prepared from animal food, or acrid and heating ali¬
ments ; and by the mixture of any noxious humours bred in the
body, or of malignant or poifonous effluvia received from the air.
(b) The blood is made to return in greater quantity to the heart
by all kinds of exercife, fudden fear, and other ftrong pallions.
(c) The fenfibility, and confequently the irritability of the
heart * is increafed by various affedlions of the mind, or whatever
increafes the general fenfibility of the nervous fyftem, by fympathy
with the other parts, efpecially the ftomach and inteftines, when
thefe are pained, or affedled with a difagreeable fenfation, by an
arthritic, fcorbutic, or fome other morbid humour thrown upon
the heart ; and by obftru&ions and inflammations in any part of
the
# See above, p, 296. &c. p. 324. &c. and where it is proved, from undoubted experi.
ments and oblervations, that the irritability of the mufcles of animals depends on their
fenfibility.