I 3 2 



ELEMENTARY ZOOLOGY. 



place the eggs where outside food suitable for the develop- 

 ing animal will be abundant, as on leaves (Fig. 26), in 

 fruits, in decaying meat, or other organic matter. After 

 hatching, the care takes the form of protection or supply- 

 ing food or both. Many animals, as the clam, some 



FIG. 26. Galls on hackberry leaf produced by a fly. Natural size. Photo by Folsom. 



Questions on the Figure. What does the gall represent from the 

 point of view of the plant? From the point of view of the insect? 

 What produces this abnormal vegetable growth? Find figures of 

 other galls and compare. Find instances of galls in nature. In 

 what ways might one determine what insect is responsible for a 

 particular kind of gall ? 



fishes, some reptiles, and the mammals retain the eggs in 

 special portions of the body until development has well 

 begun. 



An immense number of adaptations useful to the species 

 have been developed in connection with the egg-laying 

 habit. After such provision the majority of animals 

 leave the young to take care of themselves; but many 

 higher forms take further pains to protect and train the 



