THE VOICE OF ANIMALS 847 



tadpoles. When their legs are fully developed, 

 they clamber up to their father's broad mouth 

 and get their first glimpse of the great world from 

 his lower lip. When fifteen partly developed 

 polliwogs are found in the pouches of one little 

 frog, he looks as if he had gorged himself to burst- 

 ing with tadpoles. To such curious uses may vocal 

 organs be put. 



Turtles are voiceless, except at the period of 

 laying eggs, when they acquire a voice, which even 

 in the largest is very tiny and piping, like some 

 very small insect rather than a two-hundred- 

 pound tortoise. Some of the lizards utter shrill, 

 insect-like squeaks. 



A species of gecko, a small, brilliantly coloured 

 lizard, has the back of its tail armed with plates. 

 These it has a habit of rubbing together, and by 

 this means it produces a shrill, chirruping sound, 

 which actually attracts crickets and grasshoppers 

 toward the noise, so that they fall easy prey to 

 this reptilian trapper. So in colour, sound, mo- 

 tion, and many other ways, animals act and react 

 upon each other, a useful and necessary habit 

 being perverted by an enemy, so that the death of 

 the creature results. Yet it would never be claimed 

 that the lizard thought out this mimicking. It 

 probably found that certain actions resulted in the 

 approach of good dinners, and in its offspring this 

 action might be partly instinctive, and each gen- 

 eration would perpetuate it. If it had been an 



