Skin, artery, vein, and nerve, were placed with
a similar portion of muscular fibre upon a plate of
glass, in such a manner that any change in their
length would be at once observed; the glass was
then placed in water of the temperature of 120°.
being very gradually and carefully introduced
beneath its surface. The muscle contracted, but
no change was observable in any of the other
textures.
It was obvious, however, that there might be
contraction in the circular fibres of the artery or
vein, although none was observed in their length.
It was interesting therefore to ascertain whether
the form of the vessels viewed under the microscope
in their transverse sections, would be
altered. I have tried many experiments of this kind :
but I must confess that hitherto none have been
satisfactory. It still remained to determine whether
the temperature of 108°. Fahrenheit, and other
lower temperatures, would have the same influence
upon the muscular fibre as that of 120°. I ascertained
by repeated experiments that this influence
is quite distinct at a temperature below 90° ; still
more obvious at 98° ; and very prompt at 108°.—
It was a singular reflection that if the textures
of the batrachia could be for one minute bathed
with human blood at its own temperature, the
effect would be instant death to animals in many
other points of view so tenacious of life.
I have ascertained that the muscles of the warm
blooded animals are also contracted by a temperature
above that of blood heat.
. The carotid artery of a dog, from being loose
and flaccid, becomes contracted in diameter and
rigidly cylindrical, if placed in water of 120°
Fahrenheit.—The further investigations which these
facts suggest are, however, reserved for a future
opportunity.