SYSTEMATIC SYNTHESIS OF TISSUES INTO ORGANS. 205 



on the cartilages ; on the head it is called pericranium. 

 It follows the nutritious canals leading into the bone, 

 and lines the central and medullary canal and the areolae 

 of the spongy portion, under the name of endosteum. 



276. THE CENTRAL CAVITIES OF BONES, both their 

 canals and the areolse of the spongy portion, are, in 

 health, filled with marrow, the central canal with a soft 

 fat, and the spongy part with a reddish, fatty substance. 

 Both are oil deposited in nucleated cells. 



277. THE MARROW OF THE BONES SERVES to deaden 

 the effect of jars, and prevent them from reaching the 

 brain, and is a stock of calorific matter that can be taken 

 up to produce heat when a supply cannot be had from 

 without, or, from feebleness of the organs, cannot be pre- 

 pared from food. 



Special Bones of the Body. 



Fig. 157 represents a front and 

 Side view of a skull. The forms of 

 the cranium and the facium differ 

 very much in different cases. This 

 is an advanced skull, since the suture 

 or joint, like that at 3, that in early 

 life is exhibited up the centre of the 

 forehead, has been obliterated by the 

 right and left FRONTAL BONKS becom- 

 ing consolidated. A similar suture 

 is sometimes seen at maturity in the 

 middle of the upper jaw. The lower 

 jaws become consolidated at 20, very 

 early. The skull is in early life lit- 

 erally divisible into two. 



278. THE SKULL is composed of the CRANIUM, in- 

 cluding all above and back of the eye-sockets, and the 

 FACIUM, added to the lower part of the Cranium. 



276. What said of ? 277. What does ? What is the effect of water in a 

 tumbler on its vibrations ? Describe Fig. 157. 278. How divide ? 



