To Hermann Hoffmann   20 April [1871]¹

Dear Sir.

I am greatly obliged to you for your very interesting letter & for the various facts which you kindly communicate to me.—² My daughter has a little dog who acts something like yours but is not so accomplished a hypocrite;³ he likes lying on her bed, & when he hears her coming up-stairs, jumps off & settles on his own bed but does not pretend to be asleep.—

I have also to thank you for the number of the Bot Zeitung with your very curious experiments on the influence of the period of fertilisation on sex; I hope that you will continue these observations—⁴ I am convinced such experimental researches as these, & those on the struggle between different kinds of weeds, are of the highest value for natural science— And how few naturalists undertake such work!

with sincere respect & thanks— I remain. Dear Sir. | Yours very faithfully | Ch. Darwin.