Page 127 - My FlipBook

BIOLOGICAL STUDIES OX THE BACTERIA OF THE MOUTH. 101

At the June meeting of the Odontological Society of Great
Britain, 1889, Cunningham and Robinson presented impure
cultures of bacteria partly from the mouth, in wliieh well-formed
crystals might easily be seen with the naked eye. The analysis
proved these crystals to consist of the double ammonium-mag-
nesium phosphate or triple phosphate (XH^,Mg,P04,2H20).
The authors were of the opinion that " the deposition of tartar
on the teeth and the formation of some calculi in other parts of
the body may be due, in part at least, to this action." On a visit
of Dr. Cunningham to my laboratory a short time ago we ex-
amined a number of pure cultures from the mouth and found in
three cases, all from two to three months old, distinct crystalline
formations not imbedded in the growth, but projecting from it
into the pure gelatine or agar-agar.
As stated to Dr. Cunningham at the time, I am not quite
prepared to believe that this process has much to do with the
formation of tartar. Of course it remains for him to show
whether such crystals really are found in tartar, and whether
tartar actually contains the above-mentioned triple phosphate in
any consideral)le quantity.
A communication on the subject of salivary calculus by A.
C. Castle, in the January number of The Forrep, 1855, may be
of interest in this connection. He writes, " Microscopic examina-
tion discovers that this calculus exists in a crystalline state, and
by its irritating eftects frequently causes what are supposed to be
neuralgic pains.
" The next form of salivary calculus is of a soft, friable, pul-
verant nature. It is of two kinds, the simple phosphate of lime,
and the ammnniaco-magnesia phosphate of lime, with the usual
combinations of animal matter, and oxalate of lime upon investi-
gation will l)e found to exist in large quantities in those subjects
where the oxalates exist in excess."