AN INTRODUCTION TO ZOOLOGY. 



PART I. 



CHAPTER I. 



THE DISTINOTION BETWEEN ANIMALS AND 

 PLANTS. 



How are animals distinguished from plants ? is the 

 first inquiry that suggests itself, when we begin to 

 study Zoology systematically. Plants also have life, 

 as well as animals : what is the diflference between 

 them ? At first sight it seems as if this question 

 were one that could be very easily answered. Animals 

 move about, plants are fixed. Animals require to 

 breathe fresh air, from which they abstract the 

 oxygen, giving out again in return carbonic acid 

 gas, while plants absorb carbonic acid gas, and give 

 out oxygen, thereby freshening and purifying the air 

 for the further use of animals. The first distinction is 

 evident to everybody, the second is well known to the 

 student of elementary chemistry. So far, so good ; 

 but there are some cases in which such broad prin- 

 ciples as these may be diflScult to apply correctly. 

 There exists a soraewhat mythic story about two 

 Yorkshire boys, who went by dark to rob an orchard 



