AUTHOR'S PREFACE 



Sense organs have always excited general interest, 

 for they are the means of approach to the human mind. 

 Without them our intellectual life would be a blank. The 

 deaf and the blind show how serious is the loss of even a 

 single set of these organs. 



Although the ear and the eye have commonly received 

 most attention, the other sense organs, such as those of 

 smell and of taste, are in reality equally worthy of con- 

 sideration. These organs are of first significance in 

 warning us of untoward conditions that may exist about 

 us particularly in relation to our food. But they not only 

 serve us in this protective way, they are also of the utmost 

 importance in initiating that chain of events which cul- 

 minates in successful nutrition. Through their action the 

 secretion of the digestive juices and other like operations, 

 so essential to the proper treatment of the food, are 

 started and furthered in the alimentary canal. Thus 

 their activities, though less associated with our mental 

 states than are those of the ear and of the eye, are never- 

 theless so essential to our organic well-being that they 

 are in reality quite as necessary to us as the so-called 

 higher senses. 



Smell and taste, together with certain other senses not 

 so well known, form a more or less natural group in which 

 there is a certain amount of functional interrelation and 

 genetic connection, and it is from this standpoint that 

 these senses will be considered in the following pages. 

 They will thus illustrate in a way principles common to 



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