WCP1895

[1]

4 Chester Place R. Park. N.W

Until April 1^st

March 27^th [1868]¹

My dear Wallace

My son² has failed in your problem & ^says that it is "exceedingly ^excessively difficult": he says you will find something about it in Thompson & Tait Nat[ural]. Philos[ophy] (Art. 649).³ He has, however sent the solution, if the plate rested on a square rim, but he supposes this will not answer your purpose; [2] nevertheless I have forwarded it ^{by this same post.}— It seems that the rim being round makes the problem much more difficult.—

I enclose my photograph, which I have received from Down.

I sent your answer to George on his objections to your [one illeg. word crossed out] argument on sterility ^{but have not yet heard from him.}— I dread beginning to think over this fearful [3] problem, which I believe beats the plate on the circular rim; but I will sometime. I foresee, however, that there are so many doubtful points, that we shall never agree.

As far as a glance serves it seems to me, perhaps falsely, that you sometimes argue that hybrids have [4] an advantage from greater vigour, & sometimes a disadvantage from not being so well fitted to their conditions.— Heaven protect my stomach whenever I attempt following your argument.—

Your’s most sincerely | C. Darwin [signature]