TWO CHIEF CAVITIES OF THE BODY. 9 



gullet, stomach, and intestine, together form the aliment- 

 ary canal, which, as we see, begins ~on the head quite 

 above or anterior to the ventral cavity ; then, at the bot- 

 tom of the neck, enters the ventral cavity and runs on 

 through it, to pass out again posteriorly; just as a tube 

 might pass quite through a box, in at one end and out at 

 the other, without opening into it at all. In addition to 

 the lungs and the greater part of the alimentary canal, 

 the ventral cavity contains several other things of which 

 we shall have more to say presently ; among the more 

 important of them are, the heart, h ; the kidneys, k ; the 

 sympathetic nerve centers, s; and several large organs 

 making juices which are conveyed by tubes into the ali- 

 mentary canal and assist in digesting our food. 



FIG. 2. A diagrammatic section across the body in the chest region, x, the dorsal 

 tube, which contains the spinal cord; the l>lack mass surrounding it is a vertebra; 

 a, the gul lot. a. part of the alimentary canal; h, the heart; sy, sympathetic nervous 

 system; II. lungs; the dotted lines around them are the pleurae; rr, ribs; tl, the 

 breastbone. 



If we examined a section made across the trunk of the 

 body, say about the level of the middle of the chest (Fig. 

 2), we would find, on the dorsal side, the neural tube, x, 

 cut across, and in it the spinal cord, which is not repre- 



Name some organs, in addition to parts of the alimentary canal, 

 which are found in the ventral cavity. Describe what would he 

 seen on a section oiade across the hody ahout tfte middle of tb$ 

 chest, 



