From Mary Treat   11 February 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.