(seq. 127)

118

Materia Medica

Tonics

In the secretion of the gastric Juice, they certainly have this
operation, as they have been found serviceable, in promoting
digestion. Dr Darwin supposes they increase the absorption of
chyle, but I cannot think so. I judge it more probable that
many of the effects of tonics are produced by their
stimulating quality, bitters have been highly exalted for their cure in
visceral obstructions, but by ascribing to them such effects
we show our ignorance of the living system. Dr Cullen in
his long practice found them of no service, costiveness
in sedentary persons arising from torpidness of the
alimentary canal, in such cases bitters may be useful, as
diuretics. Dr Cullen says he never found their operation
manifest but they sometimes act as such as I believe all
stimulants do sometimes the Lochtransdan Taradcudine is a
bitter and a diuretic, so is opium and have been usefull
in dropseys but are of not much efficacy when given alone,
they are often joined with alkaline salts, and in this
combination the powers of each are mutually increased. Tonics
are too much neglected as diuretics. Dr Cullen says he often
found them injurious in continued fevers when there was