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forest their head-quarters. F. dardanns also often wanders 

 far afield : — one of the best places I know for it is a Bougcdn- 

 villia bush, a good 1,200 yards from the forest — and it is 

 interesting that it can do this without entirely losing the 

 protection of its Amauris models while at the same time 

 invoking, in the person of its trophonius female, that of the 

 dominant Danaine of the territory it is invading." 



The Power of Sight in Birds. — Professor Poulton said 

 that he had come across a few observations which supported 

 the conclusion that birds possessed the extraordinarily acute 

 and far-reaching vision required by the Batesian and Miillerian 

 theories of Mimicry. 



1. The distant appreciation of the colour of small insects 

 appeared to be shown by — " An Experimental Investigation 

 on the Range of Flight of Flies " by Dr. Copeman, Mr. 

 Howlett and Mr. Mei'riman (Report Loc. Gov. Bd. on Public 

 Health and Medical Subjects : New Ser., No. 53. Fui-ther 

 Reports on Flies (No. 4), 1911, p. 8). In these experiments, 

 conducted in 1910 at Post wick, about five miles east of 

 Norwich, flies were liberated after being marked with vai-ious 

 colours so that they could afterwards be identified. Yellow 

 chalk was found to give the most satisfactory results, and under 

 favourable circumstances remained perfectly recognisable for 

 a week or, on occasion, for as long as ten days. As soon as 

 these flies were liberated many of them were devoured by 

 swallows, and the authors remark " it is interesting from the 

 biological point of view, that they should readily take flies of 

 a brilliant canary-yellow colour such as they can never have 

 seen before. A few of these coloured flies that happened to 

 drop into the water were also seen to fall a prey to fish." Dr. 

 S. Monckton Copeman, F.R.S., had kindly sent a few further 

 details concerning the behaviour of the swallows : — 



"Local Government Boaud, Whitehall, S.W., 



"February 9, 1912. 

 "The swallows seemed to know when we were going to 

 let loose the coloured flies ; for although on our arrival there 

 might not be a swallow to be seen over the river, no sooner 

 had we let loose one lot of flies than there were usually a 

 number to be seen, flying up and down in front of the 



