REPRODUCTION IN ANIMALS 



329 



In some species of toads the fertilized eggs are placed in 

 the mouth of the parent, where they are kept until the tadpoles 

 are large enough to swim away. Among the batrachians, — 

 which include newts and salamanders, as well as frogs and 

 toads, — there are very many cases of parental care of the devel- 

 oping young, ranging all the way from abandonment directly 



Fig. 156. Sperm cells of animals. (Very highly magnified) 

 /, pig ; 2, bird ; j, salamander ; ^, ray ; j, threadworm {Ascaris) ; 6, lobster 



after the discharge of the gametes to guarding within the 

 body of the mother until the young are fully formed and able 

 to shift for themselves. 



382. Reproduction in the insects. Among the insects, which 

 of all animals are most distinctly adapted to living in the air, 

 the spermatozoa 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 spermatozoa pass, a few at a 

 time, into another space, wherein the female gametes (the eggs) 

 are fertilized. It is possible for a queen bee to retain a quantity 



