More Letters of Charles Darwin — Volume 2 A Record of His Work in a Series of Hitherto Unpublished Letters

LETTER 742. TO W. THISELTON-DYER. Down, October 9th, 1877.

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One line to thank you much about Mertensia. The former plant has begun to make new leaves, to my great surprise, so that I shall be now well supplied. We have worked so well with the Averrhoa that unless the second species arrives in a very good state it would be superfluous to send it. I am heartily glad that you and Mrs. Dyer are going to have a holiday. I will look at you as a dead man for the next month, and nothing shall tempt me to trouble you. But before you enter your grave aid me if you can. I want seeds of three or four plants (not Leguminosae or Cruciferae) which produce large cotyledons. I know not in the least what plants have large cotyledons. Why I want to know is as follows: The cotyledons of Cassia go to sleep, and are sensitive to a touch; but what has surprised me much is that they are in constant movement up and down. So it is with the cotyledons of the cabbage, and therefore I am very curious to ascertain how far this is general.