386 BOTANY [Chap. XI 



Letter 706 interest. There are a vast number of facts and generalisa- 

 tions of value to me, and I am struck with admiration at your 

 powers of observation. 



The discussion on mimetic insects seems to me particularly 

 good and original. Pray accept my cordial thanks for the 

 instruction and interest which I have received. 



What a loss to Natural Science our poor mutual friend 

 Walsh 1 has been ; it is a loss ever to be deplored. . . . 



Your country is far ahead of ours in some respects ; our 

 Parliament would think any man mad who should propose to 

 appoint a State Entomologist. 



Letter To C. V. Riley. 



We have found it convenient to place the two letters to Riley together, 

 rather than separate them chronologically. 



Down, Sept. 28th, 1881. 

 I must write half a dozen lines to say how much interested 

 I have been by your " Further Notes " on Pronuba? which you 

 were so kind as to send me. I had read the various criti- 

 cisms, and though I did not know what answer could be 

 made, yet I felt full confidence in your result, and now I see 

 that I was right. . . . If you make any further observation on 

 Pronuba it would, I think, be well worth while for you to 

 observe whether the moth can or does occasionally bring 

 pollen from one plant to the stigma of a distinct one, 3 for I 

 have shown that the cross-fertilisation of the flowers on the 

 same plant does very little good ; and, if I am not mistaken, 

 you believe that Pronuba gathers pollen from the same flower 

 which she fertilises. 



What interesting and beautiful observations you have made 

 on the metamorphoses of the grasshopper-destroying insects. 



of the State of Missouri (Jefferson City, Mo.). The mimetic case occurs 

 at p. 67 ; the 1875 pupae of Pterophorus periscelidactylus, the " Grapevine 

 Plume," have pupa; either green or reddish brown, the former variety 

 being found on the leaves, the latter on the brown stems of the vine. 



1 For a biographical note on Mr. Walsh, see Letter 175A, Vol. I., 

 pp. 248-49. 



2 Proc. Amer. Assoc. Adv. Sci., 1880. 



3 Riley discovered the remarkable fact that the Yucca moth {Pronuba 

 yuccasella) lays its eggs in the ovary of Yucca flowers, which it has 

 previously pollinated, thus making sure of a supply of ovules for the 

 larvae. 



