376 MISCELLANEA. [1875. 



When you come to England, I suppose that you will bring 

 Mrs. Dohrn, and we shall be delighted to see you both here. 

 I have often boasted that I have had a live Uhlan in my 

 house ! It will be very interesting to me to read your new 

 views on the ancestry of the Vertebrates. I shall be sorry to 

 give up the Ascidians, to whom I feel profound gratitude ; 

 but the great thing, as it appears to me, is that any link what- 

 ever should be found between the main divisions of the Ani- 

 mal Kingdom. . . . 



C. Darwin to August Weismann. 



Down, December 6, 1875. 



My dear Sir, — I have been profoundly interested by your 

 essay on Amblystoma,* and think that you have removed a 

 great stumbling-block in the way of Evolution. I once thought 

 of reversion in this case ; but in a crude and imperfect manner. 

 I write now to call your attention to the sterility of moths 

 when hatched out of their proper season ; I give references in 

 chapter 18 of my 'Variation under Domestication' (vol. ii. 

 p. 157, of English edition), and these cases illustrate, I think, 

 the sterility of Amblystoma. Would it not be worth while to 

 examine the reproductive organs of those individuals of wing- 

 less Hemiptera which occasionally have wings, as in the case 

 of the bed-bug. I think I have heard that the females of 

 Mutilla sometimes have wings. These cases must be due to 

 reversion. I dare say many anomalous cases will be here- 

 after explained on the same principle. 



I hinted at this explanation in the extraordinary case of 

 the black-shouldered peacock, the so-called Pavo nigripennis 

 given in my ' Var. under Domest. ; ' and I might have been 

 bolder, as the variety is in many respects intermediate between 

 the two known species. 



With much respect, 



Yours sincerely, 



Ch. Darwin. 



* ' Umwar.dlung des Axolotl.' 



