200 THE AMERICAN MONTHLY (July 
This tartar is deposited on the teeth from the lime salts 
held in suspension by the saliva, and by its gradual pre- 
cipitation becomes a hard concrete, not soluble in the or- 
dinary alkaline fluids of the mouth. In it, particles of 
food are imprisoned by daily deposition, which may re- 
main in the same condition for ages, especially if dry: 
Here, then, we have this hard, solid concrete only wait- 
ing proper treatment to disengage from its calcareous 
confinement any particles of food closely locked up in its 
mass. 
The method adopted was to clear all the tartar from the 
lower jaw and then place it ina conical drachm measure, 
to decalcify it by means of a weak dilution of hydrochlo- 
ric acid. This solution was afterwards washed away and 
the sediment examined drop by drop under the micro- 
scope, a third of an inch objective being employed in the 
examination. 
The main body of the deposit was made up of amor- 
phous particles, probably disintegrated meal of some kind. 
Interspersed were numerous granules of a siliceous na- 
ture: these were fully accounted for by the extensive 
grinding away of the summits of the molars, which were 
eroded into deep pits, and must have been productive of 
intense discomfort, not to say pain. The granules were 
found when tested by polarised light to be of two char- 
acters: some that were flinty did not answer to that test, 
while the others did so, and were stated by an eminent 
geologist to be quartzite. He explained this was proba- 
bly the result of the corn having been rubbed down in a 
roughly made quartzite mortar, with a round pebble asa 
pestle. 
Among the first organic remains to be noticed, was the 
sharply pointed tip of a small fish’s tooth, following which 
were the oval horny cells of some species of fruit resem- 
bling those going to make up the parenchyma of apples, 
then husks of corn, the hairs from the outside of the 
