730 THE POPULAR SCIENCE MONTHLY. 



quirements, while they would fail to do so in any other. These views* 

 implied that the sources of our actual vegetation and the explanation 

 of these peculiarities were to be sought in and presupposed an ancestry 

 in Pliocene or still earlier times, occupying the high northern regions. 

 And it was thought that the occurrence of peculiarly North American 

 genera in Europe, in the Tertiary period (such as taxodium, carya, 

 llquidamber, sassafras, negundo, etc.), might best be explained on the 

 assumption of early interchange and diffusion through Northern Asia, 

 rather than by that of the fabled Atlantis. The hypothesis supposed 

 a gradual modification of species in different directions under altering 

 conditions, at least to the extent of producing varieties, sub-species, 

 and representative species, as they may be variously regarded ; like- 

 wise the single and local origination of each type, which is now almost 

 universally taken for granted. 



The remarkable facts in regard to the Northeast American and 

 Northeast Asiatic floras, which these speculations were to explain, 

 have since increased in number, more especially through the admirable 

 collections of Dr. Maximowits in Japan and adjacent countries, and 

 the critical comparisons he has made and is still engaged upon. I am 

 bound to state that in a recent general work by a distinguished bota- 

 nist, Prof. Guisebach of Gottingen, these facts have been emptied of all 

 special significance,, and the relations between the Japanese and the 

 Atlantic United States floras may be said to be more intimate than 

 might be expected from the situation, climate, and present opportu- 

 nity of interchange. This extraordinary conclusion is reached by re- 

 garding 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 grew in the same 

 country, thus transferring many of my list of identical to that of rep- 

 resentative species, and by simply eliminating from consideration the 

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

 Japanese and the American plant are not exactly alike. As if, by 

 pronouncing the cabalistic word species the question was settled, or 

 rather the greater part of it remanded out of the domain of science, 

 as if, while complete identity of forms implied community of region, 

 any thing 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 like- 

 ness 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 prob- 

 able, not to say certain, and the former habitation of any of our spe- 

 cies, or if 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 ignorant when my essay was 



