I. 





ni 



fr 



iH 





if« 



« t 



^^\i 



or' 



I 



a 



:iid 



tllB 



wliicl 



,^* -^ 



He no 

 erein- 



. 4 - . 



.' '} 



pnii- 





„t<lj 



> ^-- 



into 



{ 







4 





•^.^ 





>^ 



nH^' 



Ch. XLIL] 



CHANGES CAUSED BY MAN, 



451 



number of combinations ; and it is necessarj that all these 

 should have occnrred once before the total amount of change^ 

 capable of flowing from anj new disturbing force^ can be 

 estimated. 



Thus, for example, suppose that once in two centuries a 

 frost of unusual intensity, or a volcanic eruption of great 

 violence accompanied by floods from the melting of glaciers, 

 should occur in Iceland ; or an epidemic disease, fatal to the 

 larger number of individuals of some one species, and not 

 affecting others, — these, and a variety of other contingencies, 

 all of which may occur at once, or at periods separated by 

 different intervals of time, ought to happen before it would 

 be possible for us to declare what ultimate alteration the 

 presence of any new comers, such as the bear or rein-deer 



men 



the isle. 



Every new condition in the state of the organic or inorganic 



animal 



an additional snow-clad 



creation, 



mountain^ any permanent change, however slight in compa- 

 rison to the whole, gives rise to a new order of things, and 

 may make a material change in regard to some one or more 

 species. Yet a swarm of locusts, or a frost of extreme inten- 

 sity, or an epidemic disease, may pass away without any 

 great aj^parent derangement ; no species may be lost, and all 

 may soon recover their former relative numbers, because the 



es may have visited the region again and again, 

 at preceding periods. Every plant that was incapable of 

 resisting such a degree of cold, every animal which was ex- 

 posed to be entirely cut off by an epidemic or by famine 

 caused by the consumption of vegetation by the locusts, may 

 have perished already, so that the subsequent recurrence of 



/ 



tempo 



man 



speaking, of very modern origin we may assume, although we 

 have recently obtained satisfactory proofs that he was con- 

 temporary with the mammoth and many other extinct mam- 

 malia, and that he has survived considerable changes in the 

 physical geography of the globe. 



The number of human beings uovv peopling the earth is 



G G 



