240 Mr. Home’s Observations on the Structure of 
As teeth have been hitherto considered of the same texture 
with common bone ; it is probable that nothing but the two 
substances being united in the same mass, could have led me 
to the discovery of their differing materially from each other. 
It will therefore be proper to explain, in this place, the cir- 
cumstances which first gave me the present view of the sub- 
ject. 
To obtain an accurate knowledge of the different parts of the 
elephant’s tooth, a longitudinal section was made, of one that 
was full grown. This section exposed the lateral connection 
between the different processes, and the intermediate substance 
which unites them into one mass ; it also showed the mode in 
which the processes are continued into the body of the tooth 
and fangs. 
That the internal structure might be made more distinct, 
the surface of this section was polished very highly, which led 
to the discovery of the processes of the tooth having a more 
compact texture than the intermediate substance ; for, although 
both had the same appearance after being sawn, the processes 
bore a polish, (which the other did not,)* and were laminated, 
like ivory ; while the other parts were porous, like the internal 
structure of common bone. 
This led me to examine preparations of the elephant’s teeth, in 
a growing state, preserved in spirit, which explained the mode of 
growth of these two substances to be different. In these prepa- 
* A portion of the jaw itself bore the same degree of polish as the intermediate 
substance of the tooth. 
The cells in the elephant’s skull are no part of its common structure 5 they commu- 
nicate freely with the cavity of the tympanum, and are therefore appendages to the 
organ of hearing, which I shall explain more fully on some future occasion. 
