HEARING 217 



unknown) sounds these crustaceans are said to make, we may attract 

 them by imitating krill-noises. Best of all, we might discover a special call 

 attractive to the males alone, thus automatically sparing the lives of all 

 females during the whaling season. Before progress is made in this field, 

 we must, ho^vever, have thorough knowledge of the sounds which Ceta- 

 ceans themselves produce, and of the meaning these sounds have for their 

 congeners. We shall examine this problem in the next chapter. 



