Evening star., 1932-02-22
TASTE AND SMELL
OYSTER FACULTIES,
RESEARCH SHOWS
Chemical Tests at Fisheries
Reveal Extraordinary =
Reactions.
EXPERIMENT CONDUCTED
AT FEDERAL BUREAU
Results Declared to Indicate
Strongly That Mollusks
Use Senses.
BY THOMAS r. HENRY.
ysters taste and smell.

Oysters taste and smell
Such, at least. is the implica Icn OF
tests Just reported by the Bureau Of
Fisheries. The shelled mol.usx5 snow
measurable, and in some cases specific,
responses to stimulation with cheIni al
substances which in higher animals
would result IN recognizable tastts or
odors
The experiments were conducted by
A. E. Hopkins. Bureau of Fisheries
biologist. He was able TO cut away
portions OF the shells of live oysters.
exposing rows of very short tentacles
unoer saith. Over these tentacles
streams OF various chemical solutions
were passed. Hopkins measured with
stop watch the time required for the
tentacles 10 retract when exposed 10
dlnerent chemical substances.
one OF the chemicals used was Gu
marin, which has a strong vanilla like
door. but which. in high dllutions at
least apparently is tasteless. II is
used frequently in experiments on the
sense Of smell distinguished sharply from
that OF taste with higher animals.
Hopkins found that there was a definite
response when the = marin solution
came in contact with the tentacles.
The smaller the amount o. the odorous
chemical in the solution the longer
the time which elapsed between contact
ana ro'rartion OF the tentacles. 70. the
weakest solutions used ii required IA
seconds for the reaction 20 take place
after contact. For the stronger solu-
tions there was latent pe.iod Of
slightly over 2 seconds.
Slow In Taste and Smell.
The oyster evidently is a slow smeller.
Just as later experiments showed that
ne Is Slow faster The nerve
mechanism OF stimulus and response
Wnlch is his nearest appICacn 10
mind IN the higher animals has not
Geen evolved in the direction of speed
Ihe mollusk has developed a shell in
stead OF quick reactions is a means Of
surviving in the world.
hopkins then studied the reactions
OF the oyster to quinine. whose odor Is
Iteehglo!e out whose extremely bitter
taste arouses immediate responses in
ne nlener animals. He found a quite
olHerent reaction time than to the
cumarin solutions but IT, this co . aIco
the period 'aich elapsed between C~2-
tact and <etraction OF the tcr;,cles
varied directly with the amount of
qulnlne m the solution The lnyes.i-
gator found that the oyster is .pp-oxj-
| mately eight times more sensitive IN
the qulnlne taste than is a human
peing. That Is. the weakest solution
which would cause the tentacles to
retract was only one-ei7hth as strory
as the weakest which has been found
man. --'
The quickest reaction to the cumarin
.as IN Shghtly over two seconds. while
the quickest to the quinine was in ,ass
second
question as to whether what was h7inp
simulated In the oyster was not scIna
general chemical sense and not two
olStinct senses. II the former was true
cumulative reaction was 10 be ex
pected-the extremely minute amount
OF lhe tentaclcs than would resul. from
OF me quinine resulting more rapidly
IN the reaction of the tenta oIes
than would result from the cunarir
alone. What actually happened was
that the combination produced al
most exactly the same effect as
the cumarn alone. Tie smell stimula-
tion OBVIOUSLY was dominant.
Two Senses Indicated.
Ihis indicates strongly. the report OF
the experiment points out. that two iifs
ierent senses are involved. With a
MIXED solution. IT is the sense which is
most strongly stimulated which reacts
Hep. ms was unable TO determine
whether the oyster has taste for
sweets. II it has, apparently it likes
them. Cane sugar solutions passed over
the tentacles did not produce anv re-
actioI. But the drawing up of the
tentacleS IN the cases OF cumarin and
quinine presumably was due to the fact
that the stimuli were obnoxious COM
parable 10 splitting or holding the nose
IN humans. The nervous system of the
oyster may have been so pleasantly af-
fected by the sugar that there was on
impulse to avoid il.
experiments with various salts showed
marked retractions CT the tentacles. but
the latent periods were different for diff
ferent substances. When a solution was
made up Of a salt which produced a
fast reaction when used alone and one
which produced a comparatively slow
reaction. 1t was found that the oysters
! nervous syste4n effected a compromise.
The retraction came more slowly than
with the first salt alone and more rap
idly than when only a solution of the
second salt was used. >.
This showed that the same sense was
being stimulated but in different de-
grees. The result was in striking con-
trast to the reaction with the combined
cumarin and quinine, which apparently
stimulated differentiated senses.
All the solutions were made in sea
water. so that Interpretation of the
results would not be complicated by
the possible reaction of the oyster to
some kind Of water to which its nervous
organism Is not adjusted.