MULTIPLICATION IX AXHIALS 



487 



V 



Xt^ 



358. Reproduction among batrachians. The frogs, which live 

 on land and breathe air in the adult stage, go to the edges of 

 pools and puddles at the breeding season. After the gametes are 

 thrown into the water, where fertihzation takes place, the adults 

 pay no further attention to them. In some species of toads the 

 fertilized eggs are kept in the mouth of the mother until the 

 tadpoles are large enough 

 to swim away. Several 

 species of newts and sala- 

 manders show some care 

 of the developing young, 

 ranging all the way from 

 abandoning them di- 

 rectly after discharge of 

 the gametes to guarding 

 within the body of the 

 mother until the young 

 are fully formed and able 

 to shift for themselves. 



359. Reproduction of 

 insects. Among the in- 

 sects, which of all the 

 animals are most dis- 

 tinctly adapted to living 

 in the air, the sperm cells 

 of the male are passed 

 directly into the body of 



the female through a special duct. The semen is discharged 

 into a receptacle, from which the sperm cells pass, a few at a 

 time, into another space in which the female gametes (eggs) 

 are fertilized. A queen bee can retain a quantity of living sperm 

 for two or three years, or even much longer, and can force the 

 cells out of the receptacle from time to time -as she produces 

 new eggs. Even with the insects that normally lay their eggs in 

 the water, as the mosquitoes, fertilization takes place within 

 the body of the mother. There is a wide range of variation 



J 



^ Fig. 205. Finding a home for the young 



Xest of a bluebird in natural hollow of a tree. 

 (From photograph by L. W. Brownell) 



