22 



INSECT TRANSFORMATION 



touch with the outer air through the tracheal tubes ; hence it 

 may be realized that the insect's body is admirably adapted 

 for those rapid transformations of energy which|are necessary 

 for its vigorous life-activities. 



oe. 



FIG. 12. DIGESTIVE SYSTEM OF LOCUST. 



oe, gullet ; c, crop ; sgl, salivary glands ; s, stomach ; t, intes- 

 tine ; kt, kidney or Malpighian tubes ; r, rectum. Slightly 

 magnified and somewhat diagrammatic. In part after 

 Emerton and Burmeister. 



In the great blood-cavity below the pericardial space, the 

 most prominent objects are the organs of digestion (Fig. 12). 

 The mouth, surrounded, as we have seen, with jaws for the 

 mastication of the food, leads into a narrow gullet (or oeso- 

 phagus] which widens into the large pear-shaped crop (Fig. 

 12 c) that may extend backwards into the abdomen. Along- 



