The Washington herald., 1915-06-06
Science Finds
That Insects
Smell With
Their Legs
THE Smithsonian Institution has is

THE Smithsonian Institution has is
sued a paper, by DR.. N. E. McIn-
doc, dealing with the Olfactory
Sense of Insects. which consists OF a
general review Of this unusually con-
fused subject, presenting the views Of
different authors, discussing the seat Of
the olfactory organs. summarizing the
authors experiments, and citing a large
number of scientific treatises on the SUBJ
tect, which comprises the first classified
ton of such literature.
From the views Of early writer's, in
GLIDING Aristotle, Virgil. Pliny and
others, It is evident that the belief in
sense OF smell in insects has long been
known and believed generally; also that
some insects are able to distinguish vari-
GUS odors. While it is seldom denied
that insects can smell, no one has ascer-
tanned the relative sensitiveness for any
particular species, nor is the seat OF the
organs definitely located for all species.
The writings discussed are classified
according to their viewpoints. as to the
seat OF the olfactory organs. which seems
to be the main point Of disagreement
among them. One theory which has long
since been abandoned was that these or
gans we're located in the spiracles or
HOSlEllS VI luc luoSStS, 90 III inv SoSS "-NA
the higher animals. but It was advocated
by assumption rather than experiment,
as no one has found any nerves or or
gans which suggest an olfactory func-
ton either in the spiracles, or In the
trachea, the windpipe.
One author holds that these organs
are located in the Threats OF the'various
insects; one in the mouth cavity. several
in the feelers attached to the mouth.
IN tha
nearly every available portion Of the in
sect's anatomy has been suggested by one
or another student.
Dr. McIndoo, however, has proved by
experiments that many OF these theories
are wrong. by covering up. removing or
otherwise eliminating various organs.
and testing the smell of bees. ants and
hornets thus treated. nearly all OF which
respond as readily and as quickly to the
fraction of second as normal bees, ants
and hornets under similar conditions.
About one-half of his experiments
were conducted to disprove the some
what general belief that the sense OF
smell Of insects Is located in the anten
nae, the horns or feelers attached to the
head. constituting the organs OF touch.
To this end the experimenter tested
honey-bees, ants and hornets by removing
one or both of their antennae and not
ing the.results when the insects were
subjected TO the odors from the essential
oils of peppermint. thyme and winter
green. Honey. pollen. pennyroyal.
formic acid from ants, etc, were also
used in testing the sense of smell.
After disproving the theories Of all
the other writer's concerning the seat Of
the olfactory organs. the author began
to search for organs similar to those
which he found a few years ago in
spiders These organs were soon found
on the legs and wings of all the insects
examined. Many experiments were per-
formed which proved conclusively to the
author that these organs are the true
apparatus for receiving odor stimuli in
the insects tested.
1t is certain that spiders can smell. yet
they have no antennae nor any organs
that may be compared to the antennal
organs of insects. This is another argu-
ment against the antennae being organs
of smell. All insects either have anten-
nal organs like those OF the bees, or modi-
fications of them, yet no two authors
who have studied them have agreed con-
corning their function. Such chaos can
be replaced by facts only when the be-
havior Of the insects investigated is
thoroughly studied and when expert
rents are performed in ways other than
OF the antennae alone. Then II will be
realized that the antennae can no longer
be regarded as possible seat of the
sense OF smell in insects.
In conclusion. II seems that the or
gans called the olfactory pores by the
author are the true olfactory apparatus
IN bees, ants and hornets. and possibly
IN all insects. and that the antennae play
no part in receiving odor stimuli.