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Dec. 55. I am getting to think whirlwinds must be effectual, how common waterspouts—volcanic ashes— grains of sand measured by me off Cape de Verd &c. opposed to this absence of certain orchideæ seeds very minute in Atlantic isld. & generally small distribution of orchidæ; but then bird vegetators & probably never more than 1/1000 grains. Compositæ seem fatal, Godron's fact of introduced compositæ not in Mediterranean, but time short.— but then widely distributed & great natural family & may have been altered. How common it species so peculiar to Galapagos— no whirlwinds at these islds— (Pamperos carry dust & I think seeds.) It is a known agency.— How common the pillars of sand in Deserts of Africa. Falls of fish— Take ashes as some sort of guide.— Eggs of insects and mollusca— Ask Ehrenberg grain of sand.—

Coral-isld may have received plants from old encircled land

18

[in margin:] No see Tables Decandolle vol. I p. 501-510.