122 Tue Microscope. 
tems of blood vessels, though its lacunz and cunaliculi are like 
those of bone. The larger mass of tooth substance, dentine, 
and its covering enamel are structurally unlike bone. 
In the next place, if it is toa certain extent true that “ ereat 
masses of micrococci, bacilliand leptothrix threads pass into the 
dentinal canals,” why is it left to be inferred by the reader that 
fungi penetrates the normal structure of atooth? Such an infer- 
ence would be absolutely unfounded in decay of the teeth, be- 
cause the dentinal canals thus infested were #rst penetrated by 
an agent that softened the structure. An agent is active in 
softening dentine farin advance of the localities infested by 
fungi. What the solvent is, how it is produced or maintained 
in the earious cavity are mooted questions that are not to be 
settled in any way excepting by research. This fact, however, 
is well established, and when well understood by investigation 
of the subject, it leaves one in much honest doubt about the 
direct influence of batteria in causing decay of the teeth: The 
softened dentine, characteristic of decay is always regular in 
a curved outline against the sound portion of dentine, while the 
penetration of bacteria into this softened mass is always more 
or less superficial and very irregular. None are ever found in 
the deepest portions of this mass and there are large areas often 
found in the soft mass in which there are no bacteria of any 
description. 
These facts—and they are only a few of what might be 
given—are so suggestive that a conscientious investigator will 
not be trapped into setting up a germ theory of decay of the 
teeth. 
Experiments by Dr. W. Miller go to show that the ferment 
which produces acid in the mouth is organized, and that sub- 
stances containing starch are necessary for its formation of acid. 
The unorganized ferment, ptyaline, is simply a sugar forming 
ferment. But if it is proved that bacteria produce the acid 
from certain detritus about the teeth, and that it is this acid 
which dissolves the lime salts from a tooth, neither does that 
fact qualify one to say that the disintegrating process is a germ 
disease, nor to attribute to bacteria a power which it is evident 
the organisms do not possess, because similar local conditions do 
not produce like local results. 
