NATURAL SELECTION, ETC. 117 



mg, are "neither fish, flesh, nor good red-herring," 

 being eliminated and extinguished by natural conse- 

 quence of the struggle for existence which Darwin so 

 aptly portrays. And so, perhaps, of the other pro- 

 phetic types. Here type and antitype correspond. 

 If these are true prophecies, we need not wonder that 

 some who read them in Agassiz's book will read their 

 fulfillment in Darwin's. 



Note also, in this connection, that along with a 

 wonderful persistence of type, with change of species, 

 genera, orders, etc., from formation to formation, no 

 species and no higher group which has once unequivo- 

 cally died out ever afterward reappears. Why is this, 

 but that the link of generation has been sundered ? 

 Why, on the hypothesis of independent originations, 

 were not failing species recreated, either identically or 

 with a difference, in regions eminently adapted to 

 their well-being ? To take a striking case. That no 

 part of the world now offers more suitable conditions 

 for wild horses and cattle than the pampas and other 

 plains of South America, is shown by the facility with 

 which they have there ran wild and enormously mul- 

 tiplied, since introduced from the Old World not long 

 ago. There was no wild American stock. Yet in 

 the times of the mastodon and megatherium, at the 

 dawn of the present period, wild-horses — certainly 

 very much like the existing horse — roamed over those 

 plains in abundance. On the principle of original and 

 direct created adaptation of species to climate and 

 other conditions, why were they not reproduced, when, 

 after the colder intervening era, those regions became 

 again eminently adapted to such animals ? Why, but 

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