5i)l 



nuulc I)}' Prul. Asa (Jray. '' I (jikiIi' llic al>stract of liLs virus given in liis 

 "Address". 



"^Jlie singular relations between the Japanese llora and iIkiI hI' Ndrlli- 

 eastern America gave rise to the speculalions wliicli were pnlilislicd 

 "before Heer had developed tlic rich Inssil l)()tauy ol' llir arclic zone; licliin; 

 the immense antiquity of existing si)eoi('s of plants was recognized ; and 

 before the publication of Darwin's now famous volume on the 'Origin of 

 Species' had introduced and familiarized the scientific world with those now 

 current ideas respecting the history and vicissitudes of species witli which I 

 attempied to deal in a moderate and feeble way. 



"Mv si)eculation was based upon tlie former glaciation of the northern 

 temperate zone, and tlie inference of a warmer period preceding and perhaps 

 following. 1 considered that our own present vegetation, or its proximate 

 ancestry, must have occupied the arctic and subarctic regions in I'lioceue 

 times, and that it had l)een gradually pushed southward as the temperature 

 lowered and the glaciation advanced, even beyond its present hal)itation ; that 

 plants of the same stock and kindred, probably ranging round the arctic zcnie 

 as the present arctic species do, made their forced migration southward ujjon 

 widely different longitudes, and receded more or less as tlie climate grew 

 warmer: that the general diiference of climate wiiich marks the eastern an<l 

 the western sides of the continents — the one extreme, the other mean— was 

 doubtless even then estabhshed, so that the same species and liie same sort 

 of species would be likely to secure and retain foothold in the sinular climates 

 of Japan and the Atlantic United States, l)ut not in intermediate regions of 

 different distribution of heat and moisture.: so that different species of the 

 same geiuis, as in Torreya, or different genera of the same group, as Redwood, 

 Taxodium, and Glyptostrobus, or different associations of forest-trees, might 

 establish themselves each in the region best suited to the particular require- 

 ments, while they would iivil to do so in any other. These views implied that 

 the sources of our actLuil vegetation and the explanation of these peculiarities 

 were to be sought in, and presupposed, an ancestry in Pliocene or still earlier 

 times, occupying the higher northern regions. And it was tliought that the 

 occurrence of peculiarly North American genera in Europe in the Tertiary 

 period (such as Taxodium, Carya, Liquidambar, Sassafras, Xegundo, &c.) 

 might be best explained on the assumption of early interchange and ditfusion 

 through North Asia rather tha n by that of the flibled Atlantis." 



•Memoirs of the American Academy of Arts and Sciences, vi, pp. 'm-ioS, 16iJ9. See also his 

 address at the Diibnque meeting of the American Association for the Advancement of Science, held 

 August, 1S72. Sec also American Naturalist, vi, ."wT, 1^7-,'. 



