(seq. 187)

89

Lect 7

are Cylindrical less in those, that are
flat. It has been thought that the Marrow tended
to render the Bones less brittle, but it seems rather
designed to recieive those small Ends of Vessels, which
Nourish the Bone, & to give an Oil to lubricate it -
In the spongy Part of Bones, there are a Number of
Cells lined with Membranes, which contain a reddish
Liquor, which has been called a bloody Marrow, it owes
its Colour to the Blood conveyed thro' the Fibres of the
Bones as mentioned before. This is in much greater Qua-
ntity in Children, than Adults. Of the Periosteum -
The Periosteum is a Membrane that surrounds all the
Bones, except the Teeth & Ends of Bones for Articulation
which are covered with a Cartilage to prevent Abrasion
It serves to cover the Roughnesses of Bones, & assists the
regular & easy Insertion of Blood Vessels into Bones & gives
Insertion to such Muscles, as do not require a strong Ac=
tion. It has very little Sensibility naturally, tho' when
irritated serves to admonish the Mind of any injury done
to the insensible Bone. It has a great Affinity to the
Skin, as the Disorders, that affect the Skin generally affect