( 9 } ) 
To the Cortex of the Bone, the Verio ft turn i;§ uni- 
ted, not only on the outfide, but even by entring in 
many places into the very fubrtance of the Bone, and 
is join d to it by the Veffels, which iffue out from the 
Bone, in iuch a manner, that fometimes one cannot 
determine which is the Bone, and which belongs to 
the Membrane inverting it, they both appearing in 
the Microfcope to conhrt: alike of exceeding fmall 
Veffels. 
To make this be the better underrtood, I have given 
in Fig. r. a reprelentation of a (mail part of the 
Bone, with the Periofteum adhering to it, in which 
A B CD E F reprefents the bony part, whether taken 
from an Ox, or Sheep, I do not now remember. The 
Vert oft cum is mark’d with the Letters B G H / E, the 
thicknefs of which is defign’d by BG, or IE , tho* in 
other places of the Bone, and even at no greater di- 
nance than two or three Hairs breadth, it is twice or 
thrice as thick. We fee here, that all the fmall Vef- 
fels in the Periofteum are reprefented by fo many Dots 
or Points; but in other places, where I had feveral 
times feen the Membrane of twice this thicknefs, the 
upper half of it has appear’d to be of a different make 
from the under part, for as much as in the upper part 
I could difeover nor only thofe Veffels, that had been 
cut tranfverffy, and which confequently were repre- 
sented by lb many Points, but likewife a great number 
of other Veffels running length wife along the Mem- 
brane, as is reprefented in Fig. 2. by L 0 P Jl N M, 
lam fully perfuaded, that the part reprefented by 
BGfllE, Fig. 1. is not entirely membranous, but 
that fome part of it is really bony. If we cut thro* 
the Periofteum fo deep as to divide the part of the 
Bone mark’d with the Letters A B C D E F, in the 
lame Figure, we find the fame appearance of Pores in 
O z the 
