Page 179 - My FlipBook

the mouth from the ducts of the g^Iands is usually very nearly
neutral, sometimes slightly alkaline, at other times slightly
acid, depending upon conditions of the cells and juices of the
"body. But after being poured into the mouth, micro-organisms
that cause acid fermentation are growing in it, and through
that influence it becomes gradually more and more acid as it
remains in the mouth longer. Now, during a meal great
quantities of saliva are poured into the mouth and the insali-
vation of the food goes on, and w4th the food and the drinks
that are used during the meal the acidity of the saliva is very
much lessened, or it comes to the normal and becomes very
nearly or quite neutral and the great bulk of the micro-organ-
isms are destroyed or washed away. Then after the meal, as
the saliva remains in the mouth more and there is less move-
ment of it, this growth is renewed and formation of acid by
the micro-organisms goes on and the saliva becomes more and
more distinctly acid during this time. So that we find continual
changing of the intensity of the acidity of the saliva of the
mouth from hour to hour—sometimes nearly neutral, some-
times very acid. In the hidden away places about the teeth
and about the mouth where the fluids are changed less fre-
quently, and the micro-organisms remain undisturbed, acidity
remains more or less constant. Now these are the changes
that occur in the general fluids of the mouth. If we place a
catheter in the duct of Steno wc will generally find the fluid
•coming from that duct neutral, or very nearly neutral ; from
the duct of Wharton we will find the fluid neutral or very
nearly neutral, as the rule. But if we hold the mouth open for
a considerable time, having dried the mucous membrane, and
^vatch this carefully—the roof of the mouth, for instance—we
will see little globules of a viscid fluid exuding here and there.
Now, this is the mucus that is formed by the mucous glands
situated in the mucous membrane upon the gums, upon the
Toof of the mouth, upon the buccal mucous membrane, upon
the lips, etc. These parts contain a large number of glands
that are pouring out a mucous secretion. Touching litmus to
this anywhere almost you will generally find the reaction more
•or less acid. The saliva as we find it in the mouth is made up
of all of these mingled together. So that the commingled
fluid is usually about neutral, or very slightly acid. In some
cases this mucus is large in amount, as compared with other
167