298 



PROTECTION OF YOUNG 



first few days on rich food produced in the stomach of certain .of 

 the worker bees that act as nurses. Later, thev are fed with a 



The digger wasp fills her nest with spiders stung in such a way as to paralyze and preserve 

 them. An egg is laid on each spider ; when the larva hatches it is well supplied with food. 



mixture of pollen and honey. Certain of the worker bees act as 

 soldiers to guard the hive. 



Infancy among birds. Among the birds, the new individual 

 receives a large amount of protection and food for a very long 

 period. After fertilization, which takes place inside the mother, 

 the egg immediately starts to develop. The yolk and albumen 

 represent large food supplies, and the shell is an effective protec- 

 tion. After the egg is laid in a specially made nest, the develop- 

 ing embryo is kept warm by the parent's body. This is known 

 as incubation. It makes possible a safe and rapid development. 



Both the parents of many species of birds take part in the 

 nest-building, in protecting the nest, and in incubating the eggs. 

 WTien the young of some species come out of the eggs, they are 

 fully developed and very much like the adult. The young chick, 

 for example, begins to walk and to pick up food particles almost 



