38 MECHANICAL FUNCTIONS. 



tain the size of the preceeding claw, or its mate, and this 

 is the reason why we often see, both Lobsters and Crabs, 

 with one of these parts much smaller than the other. 



INSECTS. 



This division of animals derives its name from the 

 Latin insecto, which signifies " to cut," because most of 

 them appear nearly divided by an incision through the 

 middle. 



The natural history of this class of animals affords a 

 highly interesting, useful and curious field of inquiry. 

 It is a subject, in which it appears to us, the most in- 

 curious can hardly avoid to take more or less interest, 

 since its objects are so common and so diversified in ap- 

 pearance, as to have forced themselves, more or less, on 

 the notice of every one who has his perfect senses. 



Insects have organs of locomotion, sensation, sight 

 and taste, and many of them are endowed with the most 

 wonderful instincts ; but they have neither heart, arteries 

 nor lungs, though some of them have parts analagous 

 to the two latter organs. 



Changes in the Forms of Insects. Most Insects begin 

 their lives in the form of larvae, or worms, the power of 

 flight being reserved until after having passed through 

 several preparatory changes, they attain their perfect 

 state. These changes are termed metamorphoses, and 

 are most conveniently seen, in the Lepidopterous, or But- 

 terfly tribes. 



Beginning with the hatching of the egg, laid by the 

 Butterfly, the following changes take place, before a 

 Butterfly is again produced. Most of these eggs are no 

 larger than mustard seeds, and are attached to the leaves 

 of plants on which the future larva, or caterpillar is to 

 feed. In this the Butterfly is directed by that most 

 mysterious property, called instinct, and by which she 

 never fails to place her eggs on such plants as are the 

 most proper food for her future progeny. Thus some 



What is said of the lobster acquiring a new claw in place of one de- 

 stroyed 7 Whence is the term insect derived 7 What organs have in- 

 sects ? In what form do insects begin their lives 1 



