AN OPPOETUNITY FOE NATURALISTS 209 



in the address afford some of the very best 

 material for testing the operation of Mendel's 

 Law under natural conditions. 



I wish again to caution my readers that the 

 above conclusions have been drawn from the 

 careful study of a limited number of examples. 

 Although insufficient in quantity, the English 

 material is as a whole excellent in quality. Thus, 

 many of the Pacific coast specimens were cap- 

 tured by Lord Walsingham, Dr. F. D. Godman, 

 and Mr. H. J. Elwes, and the geographical data 

 are of course as full and precise as we should 

 expect or wish. 



I trust that my brother naturalists in America 

 will make a determined attack on the fascinating 

 problems offered by the phenomena of Mimicry 

 in the North American butterfly fauna. In this 

 favoured part of the world the problems have 

 been seen to be sharp and clear as compared 

 with the almost infinite complexity of the tropics. 

 If my assistance or advice be of any value it 

 is always at the service of those who desire to 

 undertake such investigations. 



It has been abundantly shown in the course 

 of the address that immense numbers of speci- 

 mens are required from the most varied localities ; 

 and it is likely that difficulties may be presented 

 by the necessary manipulation, labelling, con- 

 venient arrangement, and permanent preservation 

 for the study of future as well as living natural- 

 p 



