As a second principle of the prosecution of
physiology, it must be assumed that no experiment
should be performed without a distinct and definite
object, and without the persuasion, after the
maturest consideration, that that object will he
attained by that "experiment, in the form of a real
and uncomplicated result.
It will be repeatedly observed during the course
of the following pages, that it is one of the most
difficult things in physiology, to devise an unequivocal
and unexceptionable experiment. I fear
most physiologists have erred in this point of
view, and have regarded and detailed, as the
simple effect of one particular cause, what was
in reality the unsuspected result of another, or
the complicated result of several.
Now an experiment made, in violation of the
first of the principles just proposed, must be
viewed aS unnecessary | an experiment made in
violation of the Second,' as useless; and both as
unjustifiable.
Equally unjustifiable is the needless repetition
of an experiment. This can only be proper where
it is incumbent upon us to satisfy the requisitions
of science, by removing a remaining source of
uncertainty or error. To repeat a physiological
experiment, in order to gratify the mere curiosity
of individuals, appears to me to be inadmissible.
It must be admitted, as a third principle in
physiological investigations, that we should not
needlessly repeat experiments which have already
been performed by physiologists of .reputation.
If a doubt respecting their accuracy, or the accuracy
.of the deductions drawn from them, arise,
it then, indeed, becomes highly important that
they should be corrected or confirmed by repetition.
This principle implies the necessity of a
due knowledge, of what has been done by preceding
physiologists. . I .shall rejoice if any thing brought
forward in this little volume,, shall induce my
readers to pore over the works of Harvey ; of
Hunter, of Haller, of Spallanzani; of Whytt,
of Legallois, of Dr Philip, of M. Flourens ; of
M,. Edwards, &c.
Having, after due consideration of these principles,
concluded, that a giyen experiment, is, at
Once, essential and adequate to the discovery of a
truth, it must next be received as an axiom, or
fourth principle, that it should be instituted with
the least possible infliction of suffering.