PREFACE. 



The word Biology, whicli seems to have been employed for 

 the first time by Treviranus, is far from bearing in the 

 scientific vocabulary a completely settled import. It may 

 not be unprofitable to determine the sense of the word. 

 EtymologicaUy it signifies literally " science of Ufe," and 

 embraces everything relating, intimately or remotely, to the 

 study of oi^anised beings ; that is to say, a whole group of 

 sciences, among which is comprehended Anthropology, for 

 instance. It is in this encyclopaedical sense that Auguste 

 Comte took the word " Biology," though as far as we our- 

 selves are concerned we intend to give it a sense much more 

 restricted. Under the designation "Biology," we merely 

 place the exposition and the coordination of all the great 

 facts and great laws of life, or nearly what is usually under- 

 stood by " General' Physiology," when this denomination is 

 applied to the two organic kingdoms. In this volume we 

 have simply attempted to state concisely what life is, and 

 how organised beings are nourished, grow, are reproduced, 

 move, feel and think. 



