326 
On the Tcdh of the Ox, Sheep, mid Pig, 
tooth sacs, serve to re-direct 
them to their proper places as 
they rise through tlie gum. But 
it may be asked, what served 
previously to carry down the 
tooth pulps aright and to form 
these guheniuculu ? It is ma- 
nifest we must ascend to a 
higher secondary law, to which 
to refer these wonderful phe- 
nomena of life."* 
To return to figure 28. 
Behind the temporary are 
seen the fourth and fifth 
permanent molars, both 
in a state of perfect de- 
velopment. Immediately 
posterior to the fifth, the 
crown of the sixth is ob- 
served coming through 
the gum, its body and 
fangs as yet covered by 
the capsule, now called 
the periodontal membrane. 
This tooth is fully up, 
namely, on a level with 
the others, by the time 
the animal is two years 
and a quarter old. 
In this illustration three 
also of the incisor teeth 
are seen to be temporary, 
having their permanent 
successors imbedded in 
the jaw beneath them, 
within their respective 
capsules. One of these 
is in a state of great for- 
wasdness compared with 
the others, as it is soon to 
be cut. The tooth marked 
1, is a permanent incisor, 
very recently put up. 
The great natural size of 
the jaw has required that 
* Physiological Anatomy, part iii., p. 180. 
t Fig. 28. One 1 .IT of the lower jaw of an ox at about two years old, dissected 
to show the condition of both the temporary and permanent teeth. Incisors : 1, per- 
