To George Henslow   11 February 1879

My dear Sir

I thank you for your kind note & for the paper hereafter to be sent.¹ You have of course the most perfect right to criticise my work in any way you think fit, & indeed it is the duty of a scientific man, when he writes, to express himself with entire frankness. I am sorry that we differ so much & fear that we shall continue to do so. But as you say truth will ultimately prevail, & we are both in search of it— Now that I am growing old, whatever I am at work on drives for the time every other subject completely out of my head; so I am a very poor critic. I will, however, hazard one remark: you say in your note “no physiological benefit (from cross-fertilisation) can be proved to be permanent”; but I never heard of any one who supposed the good effects on the offspring from crossing being more than temporary, like the effects of proper diet & other highly favourable conditions of life.—²

I remain my dear Sir | Yours faithfully | Ch. Darwin

In using the word temporary I do not mean that the good effects are necessarily confined to the first generation—