156 MIGRATION OF BIRDS. 



to have other purposes to accomplish by their 

 annual migrations. These little creatures, the food 

 of which is solely insects, could assuredly find a 

 sufficient supply of such diet during the summer 

 months, in the woods and thickets of those mild 

 regions, where they passed the season of winter, 

 and every bank and unfrequented wild would 

 furnish a secure asylum for them and their offspring 

 during the period of incubation. The passage to 

 our shores is a long and dangerous one, and some 

 imperative motive for it must exist ; and, until 

 facts manifest the reason, we may perhaps, without 

 injury to the cause of research, conjecture for what 

 object these perilous transits are made. We know 

 that all young creatures require particularly com- 

 pounded nutriment during their infant state ; and 

 nature, as far as we are acquainted with it, has 

 made in every instance provision for a supply of 

 fitting aliment. In many instances, where the 

 removal of station could not be conveniently ac- 

 complished, instinct has been given the parent to 

 provide the fitting aliment for its new-born young. 

 Thus insects, in some cases, store their cells with 

 food ready for the animation of their progeny ; in 

 others, place their eggs in such situations, as will 

 afford it when they are hatched. The mammalia, 

 at least the quadrupeds belonging to this class, 

 which could least conveniently move their station, 

 have supplies given them of a milky secretion for 



