778 BIOGRAPHICAL MEMOIRS. 



look for it in the species, partly iu the identical ones and partly in 

 those which closely answer to each other in the two floras." He acconn ts 

 for such cases as the occurrence of Phryma leptostachya in the United 

 States and Nepal as follows: "We should therefore look in one and the 

 same direction for the explanation of these extraordinary no less than 

 of the more ordinary cases of distribution, and should - - - refer 

 such anomalous distribution to very ancient dispersion." 



The plants from Japan to which he referred were collected by 

 Charles Wright, botanist of the North Pacific Exploring Expedition, 

 known as the Ringgold and Rodgers Expedition, of which Dr. Gray gave 

 an account in a paper " On the Botany of Japan, and its Relations to 

 that of North America and of other Parts of the Northern Temperate 

 Zone," presented to this academy December 14, 1858, and January 11, 

 1859, and published April 25, 1859, in the sixth volume of the Memoirs. 

 This memoir raised his reputation to its highest point among scientific 

 men, and, appealing again to the authority of Sir J. D. Hooker, "in point 

 of originality and far-reaching results was its author's opus magmim." 

 In referring to his previous paper in the American Journal, he states, 

 with great candor, that, from the facts there brought out, " (1) that a 

 large percentage of our extra-European types are shared with eastern 

 Asia, and (2) that no small part of them are unknown in western North 

 America." Mr. Bentham was the first to state the natural conclusion 

 that the interchange between the temperate floras even of the western 

 part of the Old World and of the New has mainly taken place via Asia. 

 He cites Bentham's suggestion of a continuity of territory between 

 America and Asia " under a latitude, or at any rate with a climate, more 

 meridional than would be effected by a junction through the chains of 

 the Aleutian and the Kurile Islands." He then proceeds to show why 

 a connection in a more meridional latitude need not be assumed: and, 

 fortified by the wide geological knowledge of his friend, Prof. J. D. Dana, 

 he gives a masterly account of the relations of the floras of the north 

 temperate regions from the Cretaceous i)eriod to the ])resent time, ac- 

 counting for the present distribution by migrations of species from the 

 arctic regions due principally to the different climatic conditions of the 

 pre-glacial, glacial, and post-glacial eras. The relations of the floras of 

 eastern America and eastern Asia was a favorite topic with him, and 

 he often spoke on the subject in public; his two most important ad- 

 dresses in which he referred to plant distribution being that on " Sequoia 

 and its History," delivered as retiring president of the American Asso- 

 ciation for the Advancement of Science, in 1872, and a lecture on " Forest 

 Geography and Archieology," read before the Harvard Natural History 

 Society in 1878, and afterwards translated in the Annales des Sciences. 



The study of plant distribution necessarily involved the question of 

 the origin of species, and this brings us to a consideration of the rela- 

 tions of Gray to Darwin and Darwinism, Gray first met Darwin at 

 Westbank, the residence of Sir W. J. Hooker, at Kew, in 1851; and their 



