i6 SCIEMCE PRIMERS, [§ n. 



If you cut through the skin of the neck of the rabbit, 

 you will see, first of all, muscles and nerves, and 

 several large blood-vessels ; but you will find no large 

 cavity like that in the trunk So far the neck is just 

 like the leg. But if you look carefully you will see 

 two tubes which are not blood-vessels, and the like of 

 which "ou saw nowhere in the leg. One of these 

 tubes is firm, with hardish rings in it ; it is the wind- 

 pipe or trachea ; the other is soft, and its sides fall 

 flat together ; this is the gullet or cesophagus, lead- 

 ing from the mouth to the stomach. Behind these 

 and the muscles in which they run you will find, just 

 as in the trunk, a vertebral column, without ribs, but 

 composed of bodies, and behind the bodies there is 

 a vertebral canal. This vertebral column and verte- 

 bral canal in the neck are simply continuations of 

 the vertebral column and canal of the trunk. | 



The neck, then, differs from the leg in 

 having a vertebral column and canal ivith a 

 trachea and oesophagus, and differs frcm the 

 trunk in having no cavity and no ribs. 



The head, again, is unlike all these. Indep(^ you 

 will not understand how the head is made unlbss you 

 take a rabbits skull and place it side by siie with 

 the rabbit's head. If you do this, you will at once 

 see how the mouth and throat are formed. You will 

 notice that the skull is all in one piece, except a 

 bone which you will at once recognize as the jawbone, 

 or, to speak more correctly, the lower jawbone ; Ux 

 there are two jawbones. Both these carry teeth, bit 

 the upper one is simply part of the skull, and does 

 not move ; the lower one does movt , it can be mad| 

 to shut close on the upper jaw, or can be separated \ 



