158 ESS A YS. 



Gottingen, these facts have been emptied of all special sig- 

 nificance, and the relations between the Japanese and the 

 Atlantic United States flora declared to be no more intimate 

 than might be expected from the situation, climate, and pres- 

 ent opportunity of interchange. This extraordinary conclu- 

 sion is reached by regarding as distinct species all the plants 

 common to both countries between which any differences have 

 been discerned, although such differences would probably 

 count for little if the two inhabited the same country, thus 

 transferring many of my list of identical to that of representa- 

 tive species ; and then by simply eliminating from considera- 

 tion the whole array of representative species, i. e., all cases 

 in which the Japanese and the American plant are not ex- 

 actly alike. As if, by pronouncing the cabalistic word species, 

 the question were settled, or rather the greater part of it re- 

 manded out of the domain of science ; as if, while complete 

 identity of forms implied community of origin, anything 

 short of it carried no presumption of the kind ; so leaving all 

 these singular duplicates to be wondered at, indeed, but wholly 

 beyond the reach of inquiry. 1 



Now the only known cause of such likeness is inheritance ; 

 and as all transmission of likeness is with some difference in 

 individuals, and as changed conditions have resulted, as is 

 well known, in very considerable differences, it seems to me 

 that, if the high antiquity of our actual vegetation could be 

 rendered probable, not to say certain, and the former habita- 

 tion of any of our species or of very near relatives of them in 

 high northern regions could be ascertained, my whole case 

 would be made out. The needful facts, of which I was igno- 

 rant when my essay was published, have now been for some 

 years made known, — thanks, mainly, to the researches of 

 Heer upon ample collections of arctic fossil plants. These 

 are confirmed and extended by new investigations, by Heer 

 and Lesquereux, the results of which have been indicated to 

 me by the latter. 2 



1 See Appendix, II. 



2 Reference should also be made to the extensive researches of New- 

 berry upon the tertiary and cretaceous floras of the western United 



