From Mary Treat 11 February 1875
Feb. 11, 1875.
Dear Mr. Darwin,
Some weeks ago I obtained from the ponds, simply, the long white stims of Utricularia.1 Freezing had divested them of all leaf stems. Very soon the new branches began to make their appearance, and I found, that the species that I am observing, is perfectly circinate—when the branch is wholly unrolled that is the end of its growth. These branches send off secondary branches, and then again divide and sub-divide, and with the bladders scattered among the leaves and branches, it takes but a little stretch of the imagination to make this plant equal the animal vascular system.
Look at some of the flukes—for instance, Amphistoma conicum,2 the vascular system of which, under the microscope, looks very much as this plant appears to the naked eye.
Yours gratefully | Mary Treat.
Structure of Utricularia; its resemblance to an animal vascular system.
Please cite as
Darwin Correspondence Project, “Letter no. 9853,” accessed on 13 February 2016, http://www.darwinproject.ac.uk/DCP-LETT-9853