r direction
in a fog whilst travelling in a tortuous line through broken ice. With
respect to cats, I have seen an account that in Belgium there is a
society which gives prizes to the cat which can soonest find its way
home, and for this purpose they are carried to distant parts of the
city.

Here would be a capital opportunity for trying rotation.

I am extremely glad to hear that your book will probably be translated
into English.

P.S.--I shall be much pleased to hear the result of your experiments.

LETTER 298. TO J.H. FABRE. Down, January 21st, 1881.

I am much obliged for your very interesting letter. Your results appear
to me highly important, as they eliminate one means by which animals
might perhaps recognise direction; and this, from what has been said
about savages, and from our own consciousness, seemed the most probable
means. If you think it worth while, you can of course mention my name in
relation to this subject.

Should you succeed in eliminating a sense of the magnetic currents of
the earth, you would leave the field of investigation quite open.
I suppose that even those who still believe that each species was
separately created would admit that certain animals possess some sense
by which they perceive direction, and which they use instinctively.
On mentioning the subject to my son George, who is a mathematician and
knows something about magnetism, he suggested making a very thin needle
into a magnet; then breaking it into very short pieces, which would
still be magnetic, and fastening one of these pieces with some cement on
the thorax of the insect to be experimented on.

He believes that such a little magnet, from its close proximity to
the nervous system of the insect, would affect it more than would the
terrestrial currents.

I have received your essay on Halictus (298/1. "Sur les Moeurs et la
Parthenogese des Halictes" ("Ann. Sc. Nat." IX., 1879-80).), which I am
sure that I shall read with much interest.

LETTER 299. TO T.H. HUXLEY.

(299/1. On April 9th, 1880, Mr. Huxley lectured at the Royal Institution
on "The Coming of Age of the Origin of Species." The lecture was
published in "Nature" and in Huxley's "Collected Essays," Volume II.,
page 227. Darwin's letter to Huxley on the subject is given in "Life
and Letters," III., page 240; in Huxley's reply of May 10th ("Life and
Letters of T.H. Huxley," II., page 12) he writes: "I hope you do not
imagine because I had nothing to say