SOURCE OF LIFE. 267 



easily avoid putting the question, " Why they should 

 be thus or thus." But, though a tempting question, 

 t is a dangerous one, and we must presume no more 

 than we see. From what was formerly said of the 

 germes of the oak, we may form some notion of 

 now impossible it is to trace backwards through an- 

 nual successions, and often through successions of 

 several races in the year, plants which, in their full- 

 grown state, are merely or not at all visible to the 

 eye, and animals which are equally or even more 

 minute. 



Yet why should we trouble ourselves about those 

 minute points 1 There is enough to be seen in such 

 a manner as we can understand it, in both kingdoms 

 of living and organized nature. And as the mem- 

 bers of those kingdoms are more susceptible than 

 matter deprived of life, we have them more varied 

 both by place and time. 



There is not a more beautiful study than the cli- 

 matal variation of the vegetable tribes, in their gra- 

 dation from the extreme north, where they are few, 

 to the luxuriance of the tropical forests and groves, 

 in which they not merely cover the surface of the 

 earth, but are suspended by thousands in the air, 

 without any immediate connexion with it. 



We may begin our survey at Spitzbergen, where 

 the summer is only a few weeks, and the number of 

 plants is of course very limited, or at the extreme 

 north of Baffin's Bay, where it is doubtful if there 

 be one land plant, unless we are to suppose that the 

 " red snow" is a living vegetable. But even there, 

 or at least as far in that direction as man can inhabit, 

 there is some substitute : and where the land ceases 

 to afford any thing but a place to rest on, the sea 

 still abounds with wealth. The seal and whale 

 tribes, though warm-blooded animals, and requiring 

 to breathe the free air, contrive to summer and to 

 winter there ; and in the extreme north of America, 

 the Esquimaux, who migrate a little southward iu 





