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Darwin Correspondence Project

From Mary Treat   11 February 1875

Vineland, N.J.

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.


Treat had sent CD her initial observations on Utricularia (bladderwort) in a letter of 2 December 1874 (Correspondence vol. 22).
Amphistoma conicum (now Paramphistomum cervi, rumen fluke) is a parasitic flatworm that infects ruminants such as sheep and cattle.


Structure of Utricularia; its resemblance to an animal vascular system.

Letter details

Letter no.
Mary Lua Adelia (Mary) Treat
Charles Robert Darwin
Sent from
Vineland, N.J.
Source of text
DAR 178: 177
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 9853,” accessed on 23 May 2018,

Also published in The Correspondence of Charles Darwin, vol. 23