66 The Animal Mind 



cerned in the processes whereby many animals have learned 

 to traverse a labyrinth path. 



The three classes of sensation whose existence in the ani- 

 mal mind can be most satisfactorily traced are the chemical 

 sense, under which smell and taste belong, the sense of hear- 

 ing, and the sense of sight. To the study of these the follow- 

 ing chapters will be devoted. Since the manifestations of the 

 chemical sense in the lowest forms of animals consist chiefly 

 in a differentiation of response to food and to mechanical 

 stimulation, the contact sense or sense of touch will, in dis- 

 cussing these forms, be considered along with the chemical 

 sense. 



