158 ESSAYS. 
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, 7. 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.! 
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." 
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 
