204 MR. C. F. M. SWYNNERTON ON THE 



hiis offered to see it through for me — a very laborious task, I fear. Dr. Rendle, 

 Mr. S. Moore, Mr. E. G. Baker, Mr. G. A. Boulenger, Mr. Oldfiekl Thomas, 

 and Mr. Dolhiian have all kindly helped me with identifications and often 

 sno-o-estions, and Mr. H. Eltringham with much useful suggestion and advice. 

 Mr. David Odendaal and his young brother Thompson Odendaal helped 

 very much in Africa in the collection of material, particularly for my 

 experiments on carnivorous animals. I am indebted to Mr. H. C. Bryant, 

 Dr. F. A. Dixey, Prof. Newstead, Mr. S. A. Neave, and Mr. J. 0. F. Fryer 

 for copies of their papers, a form of help that I have found very useful. 

 My kind friend, the late Miss H. J. Robins, in the midst of exacting work 

 of her own, insisted on devoting her already too scanty spare time to "helping 

 on the cause of science," as she put it, in typing for me a considerable portion 

 of the present paper. And last, but not least, I wish to acknowledge my 

 debt to my wife. Her help, which, apart from encouragement, has taken 

 the form of the papering of some thousands of insects and the laborious 

 copying out of much of my very illegible manuscript, has been invaluable. 



Interesting suggestions arising out of my results tempted me in July, 

 1911, to add very greatly to the original programme. A first attempt to 

 work out and piece together my general experimental results to that date 

 had not only shown me that that original programme was now nearly suffi- 

 ciently completed, but, in conjunction with certain of my observational 

 results, had strongly suggested considerations which, it seemed to me, would, 

 if o-enerally applicable, aid in accounting for some rather difficult facts in 

 animal coloration — including many to which " sexual selection '■' had been 

 somewhat unsuccessfully applied. 



So other animals were now to be used besides birds, other prey besides 

 insects, the main subject of enquiry was no longer to be mimicry, and such 

 further points as the validity of sexual selection were to be tested with some 

 decree of thoroughness. The net result, had I carried out my new programme 

 as fully as I intended, would have been the postponement of publication for 

 very many years more. However, both Professor Poulton and Mr. Marshall, 

 to whom I sent a first account of my results, new ideas, and further plans in 

 February of 1912, strongly, and I think rightly, urged me at least to com- 

 mence publishing my detailed experiments soon, while reserving any full 

 discussion of my main conclusions until I should have satisfied myself, by 

 means of this further work, of their probability. Hence — after a delay caused 

 by the execution of my extended programme on a smaller scale than I had 

 intended — this paper. 



My intended order of publication is as follows : — 



1. Experiments on wild birds, devised mainly to ascertain : 



(a) Whether or no they readily prey on butterflies ; 



(b) Some of theil- preferences. 



