EVOLUTION OF THE NEUROMUSCULAR MECHANISM 835 



of special sense organs at the anterior end of the animal: the sense 

 of taste at the mouth, the tactile organs found on the tentacles which 

 adorn the head of many invertebrates, and of special receptors for stim- 

 uli originating at a distance, such as the eye and ear. The development 

 of association neurons for the correlation of activities initiated by the 

 stimulation of these receptors has made this portion of the central nervous 

 system the natural place for the seat of the higher mental functions as 

 they evolved. 



