80 THB beb-kbspkr's guidb ; 



last tarsal joint are two hooked claws (Fig. 68), between which 

 are the pulvilli, which are not air-pumps as usually described, 

 but rather glands, which secrete a sticky substance which en- 

 ables insects to stick to a smooth wall, even though it be 

 above them. The legs, and in fact the whole crust, are more or 

 less dense and hard, owing to the deposit within the structure 

 of chitine. 



The hairs of insects (Fig. 26) are very various in form, 

 development and function. Some are short, others long ; some 

 simple, others beautifully feathered ; some are tactile, like 

 those of the eyes of the bees, some are protective and for 

 warmth, and some are used as brushes, combs, and for collect- 

 ing, transferring and carrying pollen. 



INTERNAL ANATOMY OF INSECTS. 



The muscles of insects are usually whitish. Sometimes I 

 have noticed quite a pinkish hue about the muscles of the 

 thorax. They vary in form and position to accord with their 

 use. The mechanism of contraction is the same as in higher 

 animals. The ultimate fibers of the voluntary muscles, when 

 highly magnified, show the striae or cross-lines, the same as do 

 the voluntary muscles of vertebrates, and are very beautiful as 

 microscopic objects. The fibers of each separate muscle are not 

 bound together by a membrane, as in higher animals. In in- 

 sects the muscles are widely distributed, though, as we should 

 expect, they are concentrated in the thorax and head. In insects 

 of swiftest flight, like the bee, the thorax (Fig. 25) is almost en- 

 tirely composed of muscles ; the oesophagus, which carries the 

 food to the stomach, being very small. At the base of the 

 jaws (Fig. 65) the muscles are large and firm. The number of 

 muscles is astounding. L,yonet counted over 3,000 in a single 

 caterpillar, nearly eight times as many as are found in the 

 human body. The strength, too, of insects is prodigious. 

 There must be quality in muscles, for muscles as large as those 

 of the elephant, and as strong as those of the flea, would hardly 

 need the fulcrum which the old philosopher demanded in order 

 to move the world. Fleas have been made to draw miniature 

 cannon, chains and wagons many hundred times heavier than 

 themselves. 



