WAYS AND MEANS OF LIVING 



living things. Therefore, animals principally have de- 

 veloped the power of movement; they have acquired grasp- 

 ing organs of some sort, a mouth, and an alimentary canal 

 for holding the food when once obtained. 



In the insects, the locomotory function is subserved by 

 the legs and by the wings. Since all these organs, the three 

 pairs of legs and the two pairs of wings, are carried by the 

 thorax (Fig. 63, Th), this region of the body is distinctly 

 the locomotor center ot the insect. The legs (Fig. 64) are 

 adapted, by modifications of structure in different species, 

 for walking, running, leaping, digging, climbing, swim- 

 ming, and for many varieties of each of these ways of pro- 

 gression, fitting each species for its particular mode of 

 living and of obtaining its food. The wings ot insects are 

 important accessions to their locomotory equipment, 

 since they greatly increase their means of getting about, 

 and thereby extend their range of feeding. The legs, fur- 

 thermore, are often modified in special ways to perform 

 some function accessory to feeding. The honeybee, as is 

 well known, has pollen-collecting brushes on its front legs 

 (Fig. 65 B), and pollen-carrying baskets on its hind legs 

 (A). The mantis, which captures other insects and eats 

 them alive, has its front legs made over into those efficient 

 organs for grasping its prey and for holding the struggling 

 victim which have already been described (Fig. 46). 



The principal organs by which insects obtain and ma- 

 nipulate their food consist of a set of appendages situated on 

 the head in the neighborhood of the mouth, which, in their 

 essential structure, are of the nature of the legs, for insects 

 have no jaws comparable with those of vertebrate animals. 

 The mouth appendages, or mouth parts as they are called, 

 are very different in form in the various groups of insects 

 that have different feeding habits, but in all cases they 

 consist of the same fundamental pieces. Most important 

 is a pair of jawlike appendages, known as the mandibles 

 (Fig. 66 B, Md), placed at the sides of the mouth (A, Md), 

 where they swing sidewise and close upon each other 



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