To Alphonse de Candolle   20 July [1868]¹

My dear Sir

I write a line merely to thank you for your kindness in telling me of your accidental error about the thorns, which I might have quoted & sh^d. probably have never observed the error.²

I will be cautious in regard to the muscles of the scalp, & will put the alternative of persistence. As these muscles are so highly variable, & are known in other to be apparently liable to reversion, this view seemed to me the most probable in the very curious case which you have given me.³

My health has failed again in the usual manner, & I have been ordered to do no work, & so have come here for some weeks entire idleness, which I find very hard work.

My wife is pleased to receive your kind remembrances.—

I do not think I expressed myself strongly enough, how much I was interested & pleased by your last long & very remarkable letter.⁴

Pray believe me with most sincere respect & thanks | yours very faithfully | Ch. Darwin