INTBOBUOTION. 7 



Animals move and have special, organs of locomotion; 

 few plants move, though minute forms have thread-like 

 processes or vibratile lashes (cilia) resembling the flagella of 

 monads, and flowers open and shut; but these motions of 

 the higher plants are purely mechanical, and not performed 

 by special organs controlled by nerves. 



Certain plants, as the sun-dew (Fig. 6), can move the 

 slender-stalked sensitive glands on their leaves, which se- 

 crete a sticky substance. When a fly alights on the leaf 

 the glands slowly bend toward the fly, and the leaf rolls 

 over so as to entrap it. The fly thus caught finally dies, 

 and its body is dissolved and digested by an acid fluid 

 formed in the leaf, whose tissues absorb the digested fly, 

 which serves as food for the plant. We thus notice in some 

 plants a process like digestion, which is peculiar to ani- 

 mals. 



Finally, animals are guided by instinct ; many insects and 

 higher animals exhibit traces of a reasoning power, and 

 lastly man, though with an animal body, possesses intellect- 

 ual, moral, and spiritual faculties. 



Definition of Zoology. — Plants form the Vegetable King- 

 dom, and animals the Animal Kingdom. The study of 

 plants is called Botany, and the study of animals Zoology; 

 while the study of living beings in general, whether plants 

 or animals, is termed Biology, which means the science of 

 living beings. 



How to Study Animals. — ^We study an animal, a fish for 

 example, by observing its form, noticing its head, trunk, 

 its fins, etc. After a long and patient examination of the 

 outside of the body we dissect it, examining the heart, 

 stomach, brain and nerves, etc., and the skeleton. After 

 a thorough study of a single specimen we should then com- 

 pare it with a frog, and thus make our studies comparative. 

 As the result of such an examination we shall obtain a f air 

 idea of the form and structure of the back-boned or verte- 

 brate animals. 



