32 INTRODUCTION. 



II. The second Section, in the natural order of study, is devoted to 

 the phenomena of the NERVOUS SYSTEM. These phenomena are not 

 exhibited by vegetables, but belong exclusively to animal organizations. 

 They bring the animal body into relation with the external world, and 

 preserve it from external dangers, by means of sensation, movement, 

 consciousness, and volition. They are more particularly distinguished 

 by the name of the animal functions. 



III. Lastly comes the study of the entire process of REPRODUCTION. 

 Its phenomena, again, with certain modifications, are met with in both 

 animals and vegetables ; and might, therefore, with some propriety, be 

 included under the head of vegetative functions. But their distinguish- 

 ing peculiarity is, that they have for their object the production of new 

 organisms, which take the place of the old and remain after they have 

 disappeared. These phenomena do not, therefore, relate to the preserva- 

 tion of the individual, but to that of the species ; and any study which 

 concerns the species comes properly after we have finished everything 

 relating to the individual. 



