322 Mr. C. F. M. Swynnerton's Experiments 



even ate more and at least as great a weight of Nepiis, 

 when thus verging continuously on the Neptis-ieiusmg 

 point, than it did of the better-liked Pyrameis at far nearer 

 repletion-point in the same space of time. The possible 

 bearing of this on some of the observations in which 

 a bird has been seen preying continuously on Danoinae 

 is obvious ; and a long-ago expressed view of Prof. 

 Poulton's, based on his own experimental results, is also 

 borne out — that it is only in the presence of pleasanter 

 insects that unpleasant species will derive advantage from 

 their special defence.* My experiments have shown, how- 

 ever, that it is a matter of relative indigestibility rather 

 than of unpalatability, that a bird can digest species of 

 prey when hungry that fail to stimulate the digestive secre- 

 tions when it is fuller, and that a bird, enabled like my 

 swallow and Lophoceros by a rapidly working digestion 

 to prey fairly continuously on low-grade prey, probably 

 never approaches repletion-point while doing so. 



1. Experiments on Dorylus (Anomma) nigricans, 

 var. molestus 



April 26th, 1911. — A large stream of driver-ants was 

 flowing in both directions between two tunnels, at the 

 foot of a steep bank and under the verandah curb 

 respectively. 



I put down in the middle of the stream four Mylabris 

 ampledens, Gerst., two Amauris albimaculafa, killed by 

 myself as I put them down and smelling strongly of 

 ordinary gas, three Epilachna polymorplia, Gerst., and a 

 Zonocerus clegans. All were at once overwhelmed by the 

 drivers, and for some minutes remained so. Ten minutes 

 later I found that the numbers clustering round the four 

 Mylabris and the three Ejnlachna had thinned considerably, 

 but the ants were still in masses on the Zonocerus and were 

 busily engaged in cutting off the wings of the Amauris. 

 A BeJenois that I now put down was attacked at once, its 

 wings cut off and left lying, and its head, thorax and 

 abdomen carried into the bank " drive " before either 

 Amauris was ready to follow it. A Rhopalocampta libeon 

 was at once seized and carried along bodily, its wings 

 being removed while it was in motion, and the two Amauris, 

 their wings left where their owners had first been put 



* Proc. Zool. Soc. Lond., 1887, p. 191. 



