172 



ZOOLOGY. 



and their food ; in each cell is deposited an egg, and a quan- 

 tity of vegetable fodder as food for the young so soon as it 

 may be hatched. 



Fig. 126. Nest of the Baya. 



Fig. 127. Nest of the Sylvia 

 Sutoria, or Tailor Bird. 



329. By instinct, animals lead a solitary life or live in 

 groups ; and these groups unite for mutual defence. Each 

 species has its own habits and its own relations with other 

 animals, with which it consorts or avoids or pursues. These 

 associations are sometimes permanent, v t others only tem- 

 porary. The hysena and wolf unite in groups only when 

 pressed by hunger. Swallows also assemble for the purpose 

 of travelling. Still more remarkable is the so-called pigeon 

 of America. They collect in almost countless millions. The 

 celebrated American ornithologist, Wilson, calculated at 

 2,000,000 a single band which he saw in Indiana; and 

 Audubon relates that one autumn day he left his house at 

 Henderson, on the banks of the Ohio, and whilst traversing 



