Darwin Correspondence Project

Cambridge. Mass,

Dec, 2. | 1872

My Dear Darwin

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

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 Dr. Rothrock, and he has sent thro' me his response.

He is in full medical practice, in the centre of Pennsylvania—in the town which was the original ``Wyoming''

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

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

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?

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