906 REPORT— 1898, 



11. Report on the Index Anirnalium. — See Reports, p. 570. 



12. Report on the Canadian Biological Station. — See Reports, p. 582. 



13. Report on the Investigatio7is made at the Marine Biological 

 Laboratory, Plymouth. — See Reports, p. 583. 



14. Report on the Occupation of a Table at the Zoological Station at 

 Naples. — See Reports, p. 587. 



15. Interim Report on Bird Migration in Great Britain and Ireland. 



See Reports, p. 569. 



16. Report on the Zoology of the Sandwich Islands. — See Reports, p. 558. 



SATURDAY, SEPTEMBER 10. 

 The Section did not meet. 



MONDAY, SEPTEMBER 12. 

 The following Papers were read : — 



1. An Experimental Inquiry into the Struggle for Existence in Certain 

 Common Insects. By Edward B. Poulton, M.A., F.R.S., Hope 

 Professor of Zoology, Oxford, and Cora B. Sanders. 



Many Lepidoptera have been proved to possess the power of adjusting the 

 larval or pupal colours to those of the immediate surroundings. This power can 

 only be exercised once in the case of the pupa (viz. at the end of larval life), and 

 rarely, if ever, more than once or twice in the case of the larva. Many naturalists 

 consider that the power is protective, and has been produced by the operation of 

 natural selection. Others have doubted this conclusion, and W. Bateson' has 

 attempted to cut away the foundation of such an interpretation as regards the 

 pupa of Vanessa urticee by arguing that there is no struggle for existence during 

 this brief stage. This argument was opposed, and the lines of an experimental 

 inquiry were suggested in the .same year by one of us.^ In the discussion which 

 followed a paper on mimicry, read before the Linnean Society on March 17, 1898,^ 

 it was strongly urged, especially by Professor Weldon, that such an experimental 

 inquiry should be conducted. Our present work is the outcome of that discussion, 

 and we desire to express our thanks to the Government Grant Committee of the 

 Royal Society for assistance in carrying on the investigation. 



• Trans. Ent. Soc. Lend. 1892, pp. 212, 213. 

 2 Poulton, Trans. Ent. Soc. Lend. 1892, pp. 471-477. 



' Poulton, Natural Selection the Cause of Mimetic Resemblance and Common 

 Wa/rning Colours. Not yet published. 



