The batrachia, as is well known to physiologists
since the days of Spallanzani, admit of
extraordinary mutilations without the immediate
extinction of life. The wound made by the
excision of the entire head m the salamander,
has perfectly cicatrized, presenting an example
of an acephalous living animal.* But such an
animal is reduced, by this very mutilation, still
lower in the scale ; and for this reason becomes
capable even of further mutilation, without the
immediate extinction of life.
It is, I believe, on this principle, that I have
been enabled to remove the whole of the brain,
medulla oblongata and medulla spinalis, in the
frog, retaining the minute and capillary circulation
; an experiment which could not succeed m
an animal of a higher order.
It will doubtless be incumbent upon us, to use
much caution in extending the facts observed in
the batrachia or in fishes, to animals higher in the
scale. It will be necessary to exercise a just degree
of reserve in passing from mere facts observed in
one order of animals, to general conclusions in
regard to others.
* M. Edwards sur les Agens Physiques, &c. p. 11.
The fact of the removal of the entire brain and
spinal marrow, in the frog, without the immediate
extinction of life, conjoined with the similar
operation upon the chick in the egg, on the third
day of incubation,1 without interfering either with
its life or developement, sufficiently establishes
the independence of the circulation of the brain
and spinal marrow, in a degree far beyond what
is' deducihle from the experiments of Whytt or
Spallanzani ; of Dr. Philip or M. Flourens.
But the latter fact, together with that of
foetuses born perfectly grown without either brain
or spinal marrow, seems to show that the functions
of nutrition and of secretion are equally independent
of the brain and spinal marrow. Is it
not probable that, if, in the experiment of removing
the brain and spinal marrow of a frog,
a stream of air were continually directed into the
cavities of the lungs, the animal would live
indefinitely, the secretions being uninterrupted ?
1 “ Si on ouvre un oeuf de poule, de canard, ou de dinde, au
troisième jour de l’incubation, on voit les mouvemens du coeur ;
si on détruit le cerveau et la moëlle épinière, le coeur continue à
se mouvoir comme auparavant, l’incubation marche, et le foetus
continue ses développemens.” Anatomie Comparée du Cerveau,
par E. R. A. Serres; Tome II. p. 224.