224 DARWINIAN!.. 



are just alike ; and, even if some difference were dis- 

 cerned between them, it would not appreciably alter 

 the question as to how such a result came to pass. 

 Each and every one of the analogous cases I ha\ e been 

 detailing — and very many more could be mentioned —  

 raises the same question, and would be satisfied with 

 the same answer. 



These singular relations attracted my curiosity 

 early in the course of my botanical studies, when com- 

 paratively few of them were known, and my serious 

 attention in later years, when I had numerous and new 

 Japanese plants to study in the collections made, by 

 Messrs. Williams and Morrow, during Commodore 

 Perry's visit in 1853, and especially, by Mr. Charles 

 "Wright, of Commodore Rodgers's expedition in 1855. 

 I then discussed this subject somewhat fully, and tabu- 

 lated the facts within my reach. 1 



This was before Heer had developed the rich fossil 

 botany of the arctic zone, before the immense antiquity 

 of existing species of plants was recognized, and before 

 the publication of Darwin's now famous volume on 

 the " Origin of Species " had introduced and familiar- 

 ized the scientific world with those now current ideas 

 respecting the history and vicissitudes of species with 

 which I attempted to deal in a moderate and feeble 

 way. 



My speculation was based upon the former glacia- 

 tion of the northern temperate zone, and the inference 

 of a warmer period preceding and perhaps following. 

 I considered that our own present vegetation, or its 

 proximate ancestry, must have occupied the arctic and 



1 " Memoirs of American Academy," vol. vi., pp. 377-458 (1859). 



