THE GRASSHOPPER 13 



are used for leaping. They are built on the same plan as the 

 others, but the femur is very much enlarged, to accommodate the 

 muscles which are used when the animal jumps. 



Food and Mouth Parts. -- Grasshoppers feed on all sorts of 

 plants and possess a set of rather complicated mouth parts for 

 holding and grinding up pieces of vegetation. These mouth 

 parts are movably attached to the underside of the head. The 

 food is held by an almost rectangular flap, in front, and a bilobed 

 flap, behind, which are known as the upper lip or labrum (Fig. 3, 

 Ib) and lower lip or labium (Fig. 3, lab). Between these flaps 

 are two pairs of grinding organs, the true jaws or mandibles 

 (Fig. 3, md), which consist each of a single thick piece and are 

 grooved, and the auxiliary jaws or maxillae (Fig. 3, mx) which 

 are made up of several pieces and serve principally to hold the 

 food between the mandibles. Both the labium and maxillae 

 bear short, jointed filaments which are supplied with organs of 

 taste, touch, or smell. By means of these organs the insect is 

 able to choose between the available food material. Biting 

 mouth parts, such as those of the grasshopper, are the simplest 

 sort found among insects. 



Digestion. - - While the food is being masticated by the jaws, 

 it is mixed with a secretion (saliva) produced by a pair of sali- 

 vary glands (Fig. 3, s.gl); this secretion passes out through a 

 salivary duct (Fig. 3, s.d). The saliva acts upon the starch in 

 the food, changing it into a more digestible substance called 

 glucose a change very similar to that which takes place in 

 our own digestive process. The masticated food mixed with 

 saliva then enters the alimentary canal. This is really a tube 

 which runs through the body and is separated into several well- 

 marked regions by constrictions. 



First, the food passes through a small tube, the oesophagus 

 (Fig. 3, #), into a large thin-walled portion, the crop (Fig. 3, cr) ; 

 here the saliva continues its action upon the starchy materials 

 in the food. In most insects the crop is followed by a thick 

 grinding organ lined with teethlike projections, but this is ab- 



