INTELLIGENCE AND INS. INCT- 



71 



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 its 

 lower end is so loosely woven, 

 that any serpent or squirrel, 

 attempting to enter the aper- 

 ture, would detach the fibres, 

 and fall to the ground. The 

 male, however, who has no 

 occasion for such protection, 

 builds his thatched dome, sim- 

 ilar to that of the female, and ^'^S- 24. 

 by its side ; but makes simply a perch across the base 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 every where exhibited 

 in the most striking manner. Bees and wasps not only 

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

 closing the cells, to deposit 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 spe<:ies 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 th-*. latter, even the kind of labor for each member 

 of the community is determined beforehand, by instinct. 



