The sun., 1893-06-04

back part OF the tongue is most sensitive 10
bittero and the tip to sweets. why saline mat
ters nre perceived most distinctly nc tno w
and acid substances Mt tho sidcs. ana "hy
there should be individual variations. rs uh-
doubtedly Is tho case. Assuming that there
are different kinds OF taste cells. 1t might DC
possible TO paralyzo somo without anecunG
others, aud thus different sensations OF taste
| might DO discrmin mated. This has. In TACT.
been done by the uso OF the leaves OF com
mon Indian plant. GDnh'na sprcSF.' -
some OF these be chewcd 1t has been found that
bittcrs and sweets are raralyzed. whlie aciuS
| and salincs are unaffected. Again. cer'"in
strengths OF dccoctons OF the leaves appear 10
| paraly2e sweets sooner than bittcrs. Iheso IN
teresting observations indicate tho eKistenceo'
different taste cells for sweets. bitters' ac,us,
| and salinos, and the inference Is Justilled that
| tho region OF the tongue most richly buppleu
| with tasto coils will respond bestto sweet SUD-
stances while another region well equipped
with taste cells sensitive to bitters Will re-
| spond best to hitter substances. me ucuuc-
| tions from the effect OF the Indian pant may
| Lc carried further Once assume set OF 'hs.o
| cells sensitive to bitter substances, and It Is
conceivable that In whatever way these were
| irritated a bitter tasto would result. III SO. a
| substance which. applied to one part OF tho
| tongue would cause n sweet sensation. might
| cause bitter IL applied to another part OF the
tongue amply supplied with taste cells sensi-
tive to btters. This may explain why sui
| phate OF magncsia eXcites at the root ot the
| tongue q bitter taste. while applied to the UP
| It causes sweet or acid taste. saccharine IN
| like mani ner Is sweet to the tip and bitter to
| the back OF tho tongue. The sensation caused
| By dropping q little vinegar on tho tongue
| Is due partly to stimulation OF the tactile
| organs and partly to stimulation OF the true
| taste cells Cocaine. the nctivo alIaioid OF the
| coca plnnt. narnlyzcs tactilo sensibilty but 1t
| is said that * tho surface OF tho tongue be
| painted with solution OF this substance ncla
| tastes become moro clear and marked. Ulti-
mntely. however. the drug affects all the end
organs. SO that linGual sensations dlsa ppeHr in
| tho following order: General sensibility and
| main, bitters, sweets. salines and acids. We
| have only to add that disease OF the tongue
| causing unnatural drynees may affect taste
| and that substances circuatin. in tho blood
| sometimes give rise to subjective gus
| tatory sensations. Thus santonlne. NOR
| phin. and hillary products as In iaun-
| dice cause bitter sensation. while
| in diabetes there is often persistent sweet
| ish taste. The insane often suffer from
! distressing subjective tastes. In such cases
| the sensation seems to be caused by irritation
| OF tho gustntory nerve or by changes in the
| taste centres OF the brain. Loss OF tasto on
| one aide Of the tongue has been observed in
| cases OF disease OF the ear involving the
| chorda nerve.
| Now for the sense OF smell. to excite which
substances must exist in the atmosphere in
| state OF fine subdivision.
OF course. even vapors and gases may be
supposed to consist OF minute molecules OF
matter How fne must be the subdivision Is
evident from the fact that II air conveying an
odor be passed through long glass tube
hacked firmly with cotton wool. 1t will still
be odorous. although this proceeding will re-
movc all particles larger than the one hun
dred thousandth OF an inch. Again. grain
OF musk will for years communicate its odor
to the air OF a room. and at the end OF tho
time. it will not have diminished np-
prsciably In weight Attempts have been
mad to discover relation that might exist
| between odors and the chemical composition
OF substances emitting them. Certain gases
| excite smell. while others are odorless. II is
found that substances OF low molecular weight
! either simply irrtate the nose or have no
| odor. Many substances which bear no re-
semblance to one another In chemical consti-
| tuition have odors that are very similar. Ar
senical compounds have the odor Of garlic.
| Nitro benzine. benzoic aldehydc. and prussic
acid have almost the same smsll. Mix sui
phuric acid with water. and an odor like that
OF musk may be given out. 1t is said that ON
eralds rubiss. and pearls IL triturated for
long time. give out O scent like that OF violets.
Again. the disease called favus. ringworm Of
the scalp. the body OF a patient sick Of typhus.
and mice have similar odora 1t Is well known
| that perfumes from very diheront sources
may be classed under certain typos. Thus
the rose type includes the Geranium. eGlantine.
ard violet ebony: the Jessamine typo. lily
OF the valley and Ylang-Ylang the orange
type. accacia and seringa. as we'll as orange
flower: the vanilla type balsam OF Peru. bon
zoin. storax. tonka bean. and heliotrope; the
lavender type. thyme and marioram: tho mint
| type balsam and sage. as we'll as peppermint;
| the musk type. amber seed as we'll AS musk:
tho fruity type. pear. apple. pineapple. and
| ounce Attempts have also been made to
| discover relation between the colors OF how-
ers and the intensity Of their perfumes Whito
flowers manifest the greatest variety OF
odors: then follow reds. yellows. green's and
green's and blues. 1t is also noticeable that
flowers which by their color emit most heat
will volatilizo the greatest amount Of perfume.
and that tho more reirangi bio the rays re-
nected from a flower. tho smaller 10
the amount OF scent. Colored sub
stances have also different powers OF ab-
sorbing slnols. Whites. yellows. reds. greens.
and blues absorb odors on decreasing scale.
1t to emit strong odor. no doubt because tho
light acts on the essential oil on which the
scent depends. Heat moro than light favors
the volatilizstion Of perfume. Hence the odors
OF flower bed In n garden are often most sp-
parent not In bright sunshine. but In the
shade. Some essential oils require higher
temperature than others to bring out their
characteristic scents.
As regards the special physiology OF smell.
1t is in the first place to be noted that the air
containing the odor must be driven against
the membrane lining the interior OF tho nose.
The nostrils may be filled with an odoriferous
substance like eau do cologne or air impreg-
mated with sulphursted hydrogen. and yet no
smell will be experienced II no inspiration is
mado. When wo make II snff, the air In the
nasal passages is rarefed. and. as the odor-
bearing alr rushes in to equilibrate the pres
sure. 1t Is forcibly driven against the olfactory