THE 



EDINBURGH NEW 



PHILOSOPHICAL JOUENAL. 



Geographical Distribution of Animals. By Professor 

 Louis Agassiz. 



The greatest obstacles in the way of investigating the laws 

 of the distribution of organized beings over the surface of our 

 globe, are to be traced to the views generally entertained 

 about their origin. There is a prevailing opinion, which 

 ascribes to all living beings upon earth one common centre 

 of origin, from which it is supposed they, in the course of 

 time, spread over wider and wider areas, till they finally came 

 into their present state of distribution ; and what gives this 

 view a higher recommendation, in the opinion of most men, is 

 the circumstance, that such a method of distribution is con- 

 sidered as revealed in our sacred writings. We hope, how- 

 ever, to be able to shew that there is no such statement in 

 the Book of Genesis ; that this doctrine of a unique centre of 

 origin, and successive distribution of all animals is of very 

 modern invention ; and that it can be traced back for scarcely 

 more than a century in the records of our science. 



There is another view to which, more recently, naturalists 

 have seemed to incline ; viz., the assuming several centres of 

 origin, from which organized beings were afterwards diffused 

 over wider areas, in the same manner as according to the 

 first theory, the difference being only in the assumption of 

 several centres of dispersion instead of a single one. 



We have recently been led to take a very different view of 

 the subject, and shall presently illustrate the facts upon 

 which the view rests. But before we undertake to introduce 

 more directly this subject, there is another point which re- 



VOL. XLIX. NO. XCVII. — JULY 1850. A 



