I now procédé to detail my own, interspersing
such remarks as appear necessary to the elucidation
of the subject.
It will be seen that whilst Legallois and Dr,
Philip occupy the extremes in opinion on the
subject of the influence of the spinal marrow upon
the circulation, M. Flourens, has adopted views
which are intermediate between these extremes,
and that since the publication of his great work,
he has arrived at other views on the subject.
1. Of the Criteria of the Power of the Action of
the Heart.
Before we can proceed with this investigation,
it is absolutely necessary to fix upon some criteria
of the effect produced. Legallois judged of the
power of the heart by the fulness of the carotids,
and by the hæmorrhage observed on amputating a
limb. Dr. Philip adopted similar modes of judgment,
adding to them the observation of the circulation
in the web of the frog. But it appears to
me essential to observe the results of the experiment
with greater minuteness.
In effect, the circulation first ceases in the
extreme, and then in the proximate parts of the
web; first in the capillaries and veins, and then in
the arteries. It may still be seen in the lung,
however, in which it ceases in the same order, in
the distant parts and capillary vessels first, then in
the larger arteries ; at length the lung ceases to be
moved by the power of the contraction of the
heart. Even at this period, the apparent action
of the heart itself is vigorous and regular, and
continues so for a very considerable time.
Criteria of the power of the heart are thus
afforded us, in the continuance of the circulation,
first in the web, and next in the lung; and lastly
in that of the beat of the heart itself.
But in some fish, especially the eel, we have a
still more' easy and accurate mode of judging of
the power of the heart and circulation. We can
readily examine, in succession, the extreme part
of the tail, and the successive portions of the dor-
sal fin; and lastly the pectoral fin. As the powers
of the heart and circulation fail, the motion of the
blood is gradually lost in portions of the fin more
and more adjacent to the heart.
But besides these modes of judging, we have
another in the periods of time, at which these
changes take place, compared with similar changes