THIRD WEEK] October 265 



develope in pools, as is ordinarily the case. So when the 

 eggs are laid, they are immediately taken by the male 

 frog and placed in these capacious sacs, which serve as 

 nurseries for them all through their hatching and growing 

 period of life. Although there is no water in these cham- 

 bers, yet their gills grow out and are reabsorbed, just as 

 is the case in ordinary 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 polywogs are 

 found in the pouches of one little frog, he looks as if he 

 had gorged himself to bursting 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, 

 motion, 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 



