THE INTRODUCTION 
and thofc parts of other bones, which are either covered with cartilages, 
or where mufcles or ligaments arife or are inferted, are covered with a fine 
membrane, which upon the fcull is called pericranium, elfewhere pe- 
riofteum. It ferves for the mufcles to Hide cafily upon, and to hinder them 
from being lacerated by the roughnefs and hardnefs of the bones, it is eve¬ 
ry where full of final 1 blood vefiels, (Tab. i.) which enter the bones for 
their nouriihment; but the internal lubfianceof the larger bones is nou- 
riflied by the vefiels, which enter obliquely through their middles, as 
has been before obferved. 
In a child who died of a fpotted fever, I found in many of the bones a 
perfedl ecchymofis, and in feveral places, particularly on the os humeri 
and os femoris, a quantity of blood between the periofieum and the bones. 
I am inclined to think that impoftumations and carious bones, which 
Ionic times follow fevers and the finall pox, may proceed from fuch ex- 
travafations of blood. 
