My Dear Darwin

My good wife duly received the new book you so kindly addressed to her, and she is delighted with the compliment.¹

I have read 20 or 30 pages— I doubt if she has got so far—for we have both been very much occupied, with visits of friends and a good many cares. I know she means to write her thanks—but how soon she may get about it is a question.

I was much interested with the few pages I have read.

I sent forward the copy to D^r. Rothrock, and he has sent thro’ me his response.²

He is in full medical practice, in the centre of Pennsylvania—in the town which was the original “Wyoming”³

Well, it is wonderful—your finding the nervous system of Dionæa!!!⁴ Pray take your time next spring, and do up both Drosera & Dionæa. I will endeavor next spring to get hold of Drosera filiformis & make the observations—⁵

I will, also, do better, by sending your note on to Mr. Canby, who lives near its habitat—& has done something already in such observations⁶

As to coiling of tendril.

I think your idea is that in the coiling of a fixed tendril, one coil has its concave side the opposite of the part that has coiled the other way.

Now, take a piece of tape say a span long; black one side, let some one hold the two ends while you twist in the middle. The two halves are coiled in opposite directions, just as a tendril which has caught does.— The same color will be on the outside of the coil all the length.

Blacken with a stroke of paint a line along the whole length of a caught tendril. On straightening it out the black will be all on one side.—

I have not had time to follow it up, and need not—since you are sure to do it. But I think it clear that one & the same side is concave—i.e. the relatively shortened side—the whole length of the caught tendril. Do not you?⁷

Mrs. Gray is absent while I write, or she would add her best regards & best wishes to my own for a happy New Year to you all.

Sincerely Yours | A. Gray