Prof. Asa Gray on Sequoia and its History. 65 



American genera in Europe in the tertiary period (such as 

 Taxoclium^ Garycij Liqiddamhar ^ Sassafras^ Negundo^ &c.) 

 might be best explained on the assumption of early inter- 

 change and diffusion through North 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, subspecies, and representative 

 species, as they may be variously regarded — likewise the sin- 

 gle and local origination of each type, which is now almost 

 universally taken for granted. 



The remarkable facts in regard to the Eastern- American 

 and Asiatic floras, which these speculations were to explain, 

 have since increased in number — more especially through the 

 admirable collections of Dr. Maximowicz in Japan and adja- 

 cent 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 dis- 

 tinguished botanist. Professor Grisebach, of Gottingen, these 

 facts have been emptied of all special significance, and the 

 relations between the Japanese and the Atlantic United States 

 floras declared to be no more intimate than might be expected 

 from the situation, climate, and present opportunity of inter- 

 change. This extraordinary conclusion is reached by regard- 

 ing 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 in- 

 habited the same country, thus transferring many of my list 

 of identical to that of representative species, and then by simply 

 eliminating from consideration the whole array of representa- 

 tive 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 were settled, or rather 

 the greater part of it remanded out of the domain of science — 

 as if, while complete identity of forms implies community of 

 region, any thing short of it carries no presvimption of tlie 

 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 m'cH 

 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 habitation of any 

 of our species, or of very near relatives of them in high northern 

 * Die Vegetation der Eido nach ilirer kliniatisclien Anordnung. 1871. 



Ann. & Mag. N. Hist. Ser. 4. Fo?. xi. 5 



