INTELLIGENCE AND INSTINCT. 47 



nus,) not only exhibits wonderful devices in the construction, 

 security, and comfort of its nest, but displays a still further 

 advance towards intelligence. The nest is built at the tips 

 of long pendulous twigs, usually hanging over the water. It 

 is composed of grass, in such a manner as to form a com- 

 plete thatch. The entrance 

 is through a long tube run- 

 ning downwards from the 

 edge of the nest ; and the 

 lower end of it is so imper- 

 fectly woven, that any ser- 

 pent or squirrel, in attempting 

 to enter the aperture, would 

 detach the fibres, and fall to 

 the ground. But the male, 

 who has no occasion for a 

 nest, builds his thatched dome, 

 similar to that of the female, Fig. 24. 



and by its side ; but makes simply a perch across the bottom 

 of the dome, without the nest-pouch or tube. 



141. But it is among insects, that this instinctive solici- 

 tude for the welfare of the progeny is everywhere exhibited 

 in the most striking manner. The bees and wasps not only 

 prepare cells for each of their eggs, but take care, before 

 closing the cells, to deposite in each of them something ap- 

 propriate for the nourishment of the future young. 



142. It is by the dictate of instinct also, that vast numbers 

 of animals of the same species associate, at certain periods 

 of the year, for migration from one region to another ; as 

 the swallows and passenger pigeons, which are sometimes 

 met with in countless flocks. 



143. Other animals live naturally in large societies, and 

 labor in common. This is the case with the ants and bees. 

 Among the latter, even the kind of labor for each member 

 of the community is determined beforehand, by instinct. 



