111 lilM.RAI. STRUCTURE OF THE BODY 15 



whicli can be bent t> ;i Mn;ill extent in various directions, may 

 be felt running down the middle from the head to the tail. 



Cut through the skin, and only the skin, of the thorax and 

 abdomen in the middle line, turn it back on each side, divid- 

 ing it in one or two places so that the front of the animal is 

 laid bare. Stretching from the sternum and the upper ribs to 

 the forelimb on each side is a large mass of flesh or muscle. 

 Cut through this muscle on each side close to the sternum, 

 and turn it outwards towards the limb. The ribs and sternum 

 will then be distinctly seen. They are greyish in colour, and 

 consist of bone. The ribs at their front ends before they reach 

 the sternum suddenly become white in colour, and softer to 

 the touch. These ends do not consist of bone, but of car- 

 tilage. The lower end of the sternum forms a thin plate 

 which consists also of cartilage. See that the ribs can be traced 

 back to the vertebral column. Between them, and connecting 

 them to one another, are muscles, the intercostal muscles. 



The abdomen is still closed by, in addition to the skin, a 

 thin wall made up of thin sheets of muscle on each side, which 

 meet in the white line running down the middle. This white 

 line is of a fibrous nature, called tendon. There is often a 

 good deal of fat lying just underneath the skin, and covering 

 the thin muscular wall of the abdomen. The muscular wall of 

 the abdomen extends backwards on each side to the vertebral 

 column, and downwards to the hip bones, from which the 

 lower limbs arise. 



Carefully cut through the wall of the abdomen in the middle 

 line from the lower end of the sternum downwards, and make 

 .me or two transverse cuts in the wall on each side, so that the 

 contents of the abdomen are well seen. Raise the lower end 

 of the sternum, and gently draw down the organs or viscera, 

 which lie just below it ; you will then see a partition, which 

 is thin and almost transparent in the middle, stretching right 

 across the body, and completely separating the abdomen from 

 the thorax. This partition is the diaphragm 



Without disturbing the viscera at all, the following organs 

 will be seen in the abdomen : 



i. The liver (L). A. dark-red mass, in several parts, called 

 lobes, situated immediately below the diaphragm, with 

 the gall-bladder which appears green on its front edge. 



