46 INTRODUCTION. 



most interesting is, that certain land birds leave us in the spring 

 to nidificate in other countries, a fact to be accounted for only 

 by looking to higher causes. The regions of the East would, 

 doubtless, supply the Swallow with food inexhaustible through- 

 out the year ; the Nightingale, and other warblers, would find 

 no difficulty in supplying their wants in those genial climes ; and 

 yet, urged by an irresistible and regularly recurring impulse, 

 they launch forth on a wearisome and perilous voyage to fulfil 

 their high mission. The same principle must apply to those 

 birds which hybernate with us. The cone of the fir-tree is 

 nearly as abundant as in the north, and yet the Cross-bill, Haw- 

 finch, and Chatterer, leave us ; berries are as plentiful, and still 

 the Fieldfare and Hedwing return in flocks. As regards the in- 

 sectivores, I believe them to be commissioned by an all- wise and 

 all-beneficent Providence, to free us from the crowd of insects 

 which would otherwise infest our dwellings, and destroy the 

 labours of the field ; and how greatly do they add to our enjoy- 

 ments and feelings of cheerfulness by their beauty, motions, 

 and melody ! May not the return of the migratory birds to the 

 north be designed for the same purpose ? for how vast would be 

 the abstraction from our enjoyments, were our woods and hedge- 

 rows silent and tenantless. If our more southern winter is 

 gladdened and enlivened by these sportive and happy beings, 

 the vernal and summer delights of the inhabitants of the less 

 genial regions of the north are increased, and the privations of 

 winter, in a measure, compensated for by their return." 



The following very suggestive'remarks on this head, are from 

 KNAPP'S Journal of a Naturalist. " We know that all young 

 creatures require particularly, compounded nutriment during 

 their infant state ; and nature (Divine Providence), 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 re- 

 moval of station could not be conveniently accomplished, 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 ntammalia at least the quadrupeds belonging to 

 this class, which could least conveniently move their station have 

 supplies given them of a milky secretion for this purpose. Birds 

 have nothing of this nature, and insects no provision for their 

 young ; but they, of all creatures except fishes, can seek what 

 may be required in distant stations with most facility. A suf- 

 ficiency of food for the adult parent may be found in every 

 climate, yet the aliment necessary for its offspring may not. 

 Countries, and even counties, produce insects that differ, if not 



