1921] The Age of Insects - 23 



perhaps aid in conveying the complexity of the subject. We have, 

 as our most generahzed, the chewing insects which are fitted with a 

 pair of mandibles which tear and masticate food. 



A scraping type which lacerates the epidermis of plants and sucks 

 up the exuding sap. 



A piercing type in which the mouth parts are fitted for piercing 

 the skin of an animal or the epidermis of a plant and sucking the blood 

 or sap. 



A rasping type fitted for rasping off solid particles and dissolving 

 them in saliva and then sucking up the resultant hquid. 



A sponging type in which the mouth parts are fitted for sponging 

 up exposed liquids. 



A siphoning type in which the mouth parts are formed into a long 

 hollow tube which is usually used to suck up exposed nectar. 



A lapping type in which the mandibles are well developed for work- 

 ing wax and paper or for portage and the other mouth parts are modi- 

 fied into a tongue which is used to lap up exposed liquids. 



The thorax is largely given over to locomotion, which is carried on 

 by the wings and legs. The insects were without doubt the first ani- 

 mals to conquer the air and of all animals, birds not even excepted, their 

 mastery of the air is the most complete. The legs are fitted chiefly 

 for walking, running, leaping and grasping. The speed of certain of 

 our insects is indeed remarkable, as is their ability to make surprising 

 leaps. The world's record for the broad jump is not held by a man 

 but undoubtedly belongs to the flea. A leap of a hundred times his 

 length would be no astounding feat for a flea, whereas for man five or 

 six times his length would be wonderful indeed. In the same way the 

 muscular strength of insects is almost beyond belief. The weakest 

 insects according to Plateau can pull five times their own weight, while 

 the average is more than twenty times, and one of the leaf beetles can 

 pull forty-two times its own weight. In contrast man cannot pull 

 his own weight and under the same conditions a horse could pull but 

 three-quarters of his weight. Some of the insects are able to push one 

 hundred times their own weight, while the honey bee can carry a load 

 equal to three-fourths of its bodily weight. These remarkable feats 

 are accounted for by the small size of the insects and by the greater 

 advantage in leverage from an external skeleton. 



Passing to the internal organs we find time for the discussion o 

 two systems of organs only. The first of these is the respiratory or 



