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Jan. 29t h. /42/. Humboldt descanted on remarkable fact (as observed by Gmelin & Pallas) that the banks of the River Oby separates two Floras—on one side 810 of plants same as in Germany with 210 Asiatic—on other side reversed large proportion of Asiatic.— Remarked a similar case with respect to the distribution of oaks in some place, I did not catch up—with Astacus in all the brooks on one side & not on the other: says Bellis perennis extends to a certain limit & then ceases, but it is not the cold, for this plant will flower, far within the limits of snow on some mountains— On the Oby there is no geological change — — prepossession  of soil must here have done much.— ⸮Have two Floras marched from opposite sides & met here??—strange case.—