THE REASON WHY. 219 



"Our bones are scattered at the grave's mouth, as when one cutteth and 

 cleaveth wood upon the earth." PSALM CXLI. 



Arms and Hands . * . .64 



Legs and Feet '-, 62 



Small moveable bones ... 8 



924. Of what substances are the bones composed ? 



One hundred parts of bone consist of 



Cartilage . . . . 3217 parts 

 Blood-vessels *. - . '. T13 



Carbonate of lime .... 11*30 



Phosphate of lime . . . 51'04 



Fluate of lime 2'00 



Phosphate of Magnesia . . 1'16 



Soda, chloride of sodium . . 1'20 



100-00 



925. What are the uses of the bones ? 



They protect soft and delicate organs ; they form a framework to 

 vhich the organs are attached, and by which they are kept in their 

 places; and they supply a mechanism, by which the motions of the 

 body are produced, in combination with the muscles. 



926. Why is the brain placed within the skull ? 



Because that delicate and vital organ, being the centre and the 

 root of the nervous system, requires a position of the greatest safety. 



927. Why are the bones that constitute the vertebrae 

 (back-bone) \ollowed out, so as to form a continuous groove? 



Because thiough that groove the spinal cord passes out from the 

 brain. Being in the centre of that column of bones, the spinal cord 

 receives from them a similar protection to that which the brain 

 obtains from the skull. 



928. Why is the head set upon the neck ? 



Because in that position it obtains the freest motion, can turn in 

 any direction, and is placed relatively to the other parts of the 

 body, in that situation where it acquires the greatest possible 

 advantage. 



929. Why are the eyes placed in the sockets of the skull ? 

 Because the bones of the skull afford protection to the delicate 



