

OUTLINES 



OF 



NATURAL HISTORY. 



CHAPTER I. 



INTRODUCTORY. 



Before commencing the proper subject of this work — 

 namely, a consideration of the leading types of structure 

 as exhibited in the different classes of animals — it may be 

 well briefly to consider how an animal lives. Without 

 entering into any consideration of the much-vexed ques- 

 tion whether the substance which composes the bodies of 

 animals is in all cases substantially the same or not, it 

 remains certain that the mere act of living is, in all cases, 

 attended with more or less destruction of the material of 

 which the living body is composed. Every vital act, of 

 whatever kind, is attended by a destruction of the tissue 

 which is concerned in the act. Thus, every movement 

 of the body is effected at the expense of some muscle, and 

 every thought we think is attended by a destruction of 

 a portion of the substance of the brain. Hence comes 

 the notorious fact that no animal can exist without food. 



Ministry of EJucaUon, Ontario 

 Historical Collection 



