It was more remarkable to observe that the birds paid not the slightest attention to gaudy caterpillars, not even when in motion,--the experiments so thoroughly satisfied my mind that I have now given up making them." LETTER 269.

TO LAWSON TAIT.
(269/1.

The late Mr.Lawson Tait wrote to Mr.Darwin (June 2nd, 1875): "I am watching a lot of my mice from whom I removed the tails at birth, and I am coming to the conclusion that the essential use of the tail there is as a recording organ--that is, they record in their memories the corners they turn and the height of the holes they pass through by touching them with their tails." Mr.Darwin was interested in the idea because "some German sneered at Natural Selection and instanced the tails of mice.") June 11th, 1875.
It has just occurred to me to look at the "Origin of Species" (Edition VI., page 170), and it is certain that Bronn, in the appended chapter to his translation of my book into german, did advance ears and tail of various species of mice as a difficulty opposed to Natural Selection.

I answered with respect to ears by alluding to Schobl's curious paper (I forget when published) (269/2.

J.Schobl, "Das aussere Ohr der Mause als wichtiges Tastorgan." "Archiv.