Wood County reporter. [volume] (Grand Rapids [i.e. Wisconsin Rapids], Wis.) 1857-1923, 1886-09-16
THE SENSE OF SMELL.
Its Wonderful Delicacy in Detecting Minute
Subdivision OF Matter.
Medical Record.
partner.

Medical Record.
The sense of smell is probably the lead
ing sensOrial endowment in most insects
and it does for them what sight and hear
ing do for man. Its potency in helping
along intelligence is very great, since we
know that, mentally, insects stand at
the head of the invertebrate, as man
stands at the head of the vertebrate world.
The sense of smell is probably acute in
some fishes, as for example, the shark
this is the most active, if not the most in
telligent Of fishes, and it has an OlfactOry
mucus membrane which, if spread out,
would cover some twelve square feet.
The sense falls in value in the
amphiba reptiles and birds, but
rises again in the mammalia, though
not in proportion to intelligence. It's ex-
treme acuteness in the dog, the most in
telligent of animals short of quarumana,
is well known. In man the sense of
smell is subordinate, and even rubin len
try. Olfaction adds to mans enjoy
ment, preserves him from some dangers,
but does not very much extend his knowl-
edge of his environment. Yet, despite
the comparative insignifcance of this
sense in man, its delicacy is most marvel
Gus, and by it we can appreciate more
impact of more infinitesimal molecular
vibrations than by any other avenues to
the brain. Professor Valentine has made
some interesting and striking expert
ment in proof of this. He found that a
current of air containing 100000 MILL
gramme of promine, or 1900, MILL
gramme of sulphureted by
drogen, or 100000 milligramme of oil
of roses could be perceived by the sense
of smell. He also determined that
the amount of odoriferous air which must
pass over the olfactory membrane in order
to excite the sense of smell was from so
to 100 cubic centimeter Zone tenth to
oneffth of pint. He calculated, there
fore, that the actual amount of brOmine
necessary to excite sesse of smell was
1000 milligramme, of sulphureted hyd-
rogen $4,000 milligramme, of oil
of roses 100000 milligramme (abOut
1-120,tO0 of a grain). Two recent
experimenters, E. Fisher and F. Pent-
zoldt of Erlangen, have found two other
substances which far exceed the fore
going in their capacity for affecting the
Olfactory nerves. These were mercaptan
(sulphureted alcohol and chlorphenol.
They found that in air containing
1880, 900 milligramme to the cubic
centimeter of chlorphenol and 1-23,-
O0O,OO0,O0O milligramme of mercaptan,
these substances could be appreciated,
and twas estimated that only IA, 100000
milligramme of chlorphenol, and 1-46O,-
100000 milligramme of mercaptan, is nee
essary to excite sensation of smell.
There exists, therefore, substance which
is so small subdivision as 12,760,O0O,000
grain, or not quite one-third billionth of a
grain, is capable of calling out nerve
impulse. This subdivision of matter is
quite beyond comprehension, yet the nose
alone can appreciate it. The smallest
subdivision appreciate by the eye
through the spectroscope ISL 100000
milligramme of sodium, which is $50
times coarser division of matter than the
odor exciting power of mercaptan it is
proposed to put it to some practical use
in testing currents of air, ventilation. etc.