WAYS AND MEANS OF LIVING 



mouth parts fitted for sucking, or for piercing and sucking. 

 Some of the sucking types of mouth parts will be described 

 in other chapters (Figs. 121, 163, 183), but it will be seen 

 that all are merely adaptations of form based on the ordi- 

 nary biting type of mouth appendages. The fossil records 

 of the history of insects show that the sucking insects are 

 the more recent products of evolution, since all the earlier 

 kinds of insects, the cockroaches and their kin, have 

 tvpical biting mouth parts. 



The principal thing to observe concerning the organs of 

 feeding, in a study of the physiological aspect of anatomy, 

 is that they serve in all cases to pass the natural food 

 materials from the outside of the animal into the alimen- 

 tary canal, and to give them whatever crushing or masti- 

 cation is necessary. It is within the alimentary canal, 

 therefore, that the next steps toward the final nutrition 

 of the animal take place. 



The alimentary canal of most insects is a simple tube 

 (Fig. 68), extending either straight through the body, or 



AInt Mint Reo-t 



-An 



Fie;. 68. The alimentary canal of a grasshopper 



Ahit, anterior intestine; An t anus; Cr, crop; GC, gastric caeca, pouches of the 

 stomach; Hphy, hypopharynx (tongue); Lb, base of labium; Mai, Malpighian 

 tubules; Mint, mid-intestine; Mth, mouth; Oe, oesophagus; Reel, hind intestine 

 (rectum); SIGI, salivary glands opening by their united ducts at base of hypo- 

 pharynx; Vent, ventriculus (stomach) 



making only a few turns or loops in its course. It con- 

 sists of three principal parts, of which the middle part is 

 the true stomach, or ventriculus {Vent) as it is called by 

 insect anatomists. The first part of the tube includes a 



[ 109] 



