46 THE ORIGIN OF THE EAR. 



Recent discoveries in regard to the sense cells and 

 sensory nerve fibers in the common earthworm. 



A comparison of these scattered sense cells and fibers 

 to those of the organs of special sense. 



The origin of the sense organs as the result of 

 high differentiation, and specialization of cells of the 

 epidermis which are uniformly alike. A further illus- 

 tration of the principles of physiological division of 

 labor. 



The relation of the subject of the origin of the sense 

 organs to that of the origin of the senses, and of the 

 origin of all that depends upon the senses. 



