National Baptist world., 1894-09-21
EXPERIMENTS ON SNAILS,
they Will Live Under Conditions Which
Would Appear to Ee Fatal

Would Appear to Be Fatal.
Spallanzani has proved that the COM
mon snail may be deprived of any of
the four conditions of life and yet sur
vive. 1t simply retires within it's she'll
and goes to sleep. Spallanzani cut
/ small openings in the shells of the
! snalls. Through these he could clearly
see the functions of life in operation.
AS the temperature gradually dimin-
ished these opera tions became weaker
and weaker; at naught degrees all move
ments ceased, and the snail appeared to
be dead. AS soon as the temperature
was raised movements indicative of life
began again: by raising the tempera-
gained its normal powers. Thus the
eXperimenter quickened and reduced
life at his pleasure.
To prove that the absence of heat
suspends the snail's animation through
the winter season, Spallanzani made
the following experiments: When the
snail retired within it's shell it closed
it hermetically, and both shell and
orperculum were impenetrable to air
Operculum and fastened a fine glass
tube in it, excluding the possibility of
air getting in. He then placed the
snail under water and forced air into
the shell through the tube. If there
were any fine openings in the shell or
the operculum. or if the snail before
entering had filed the shell with air,
the air forced into it by means of the
tube would cause air bubbles to be
visible through the shell, but Spal-
lanzani could not detect any. He made
another experiment to test this.
He bored a hole in the operculm of
another snail, and again fitted an air
tight glass tube into it and filled the
tube with quicksilver. He then turned
tube and snail upside down and dipped
the end of the tube into a cup filled
with quicksilver. If the snails shell
was absolutely without air the tube
would show it, for it would act like
barometer Spallanzani found that
there was no air inside of the shell.
During the winter he placed several
small barometers" side by side with
ordinary barometers for comparison
The snail barOmeters'' acted exactly
as the regular barometers.
SpallanZani, however, went further
1t was possible, he thought, that the
snail before shutting himself up, might
have laid in supply of air. He there
fore extended his experiments to many
specimens, making examinations just
after the snail had retired, in the mid
die of winter, and in the spring, and
proved to his satisfaction that the snail
had not breathed during the winter. He
also kept number of snails dur
ing the winter on the bottoms of glass
jarf filed with water. oil and quick
silver, proving conclusively that they
had no air supply during that time.
To prove that it is want of oxygen
that puts snails tosleep, he set them in
a vessel filled with hydrogen. For |
about ten minutes the interior organs
acted as usual, breathing the hydrogen,
but they suddenly ceased, and the snail
closed the shell by the operculum and |
lay still. At the end of five hours
Spallanzani forced little atmospheric
air into the lungs of the snail, and al
most Immediately the heart began to
act and the blood to circulate. When
he stopped to supply the air the opera.
tions of life also stopped. The snail
immobile when carbonic acid
gas or hydrogen was forced in. 1t is,
the oxygen which sets
the organism in notion
Naturen of Mennesket.