148 



and then falling had been brought by the waves, cannot 

 certainly be ascertained; but Kalm's observation in- 

 clines me to the latter opinion*." And Sir Charles 

 Lyell remarks : " Exotic beetles are sometimes thrown 

 on our shore, which revive after being drenched in salt 

 waterf." Nor should we forget that chance agencies of 

 every description, which we are too apt to overlook, are 

 daily at work (and have been so since, at any rate, the 

 last creative epoch) to transport these variously organized 

 beings beyond their original spheres. Sometimes they 

 are carried on, or within, the bodies of larger animals, 

 which is especially the case with the parasitic tribes ; at 

 others on floating trunks of trees, and casual substances 

 of divers kinds, which are able to resist for a definite 

 period the destructive action of an element saturated 

 with salt. Unwilling victims, again, are ever and anon 

 hurried to comparatively distant lands by the very 

 winds that blow ; and not only to distant lands, but 

 over altitudes in which the severity of the cold would 

 quickly annihilate them, were they (as perhaps usually 

 happens) to be deposited there on their headlong and 

 compulsory course. " As almost aD insects are winged J," 

 says Sir Charles Lyell, " they can readily spread them- 

 selves wherever their progress is not opposed by un- 



* Introduction to Entomology, ii. p. 13. 



t Principles of Geology, 9th ed. p. 657. 



J Although this is true on a broad scale, a reference to my ob- 

 servations in a preceding chapter will show, that in some countries, 

 especially islands, the reverse will frequently be found to obtain. 



