Where did Life Begin? 27 



first habitable zone included the northernmost 

 land of all the great continents which con- 

 verge around the north pole, this dispersion 

 from an increasing cold to the north of each 

 of them would have sent southward plants 

 and animals from a common origin and ances- 

 try, to people and to plant all the continents 

 of the earth, with the possible exception ol 

 Australia, whose flora and fauna are certainly 

 anomalous and possibly indigenous. 



I have mentioned cold as the all-sufficient 

 cause of a dispersion to the southward ol 

 plants and animals. To those who would ad- 

 mit the cause but doubt the effect, I would 

 quote a sentence from the admirable book of 

 Professor Dana, entitled *'The Geological 

 Story Briefly Told," in which he says (speak- 

 ing of the glacial epoch, page 224) : ''There 

 must have been some exterminations as a con- 

 sequence of the cold of the glacial period and 

 of the ice of the high latitude regions ; Tnany 

 plants were driven south by the coming on of 

 the cold, and thus escaped destruction, and 

 some of these nozv live on Mo2tnt Washi^ig- 

 to7t and other high stifninits of temperate North 



