7 
“4 
D.—ZOOLOGY. 93 
Of more importance, because common to many species and known to 
exist in all the great tropical areas, is the nesting association between 
birds and the most formidable of insects—wasps and hornets; also with 
ants and termites. In the association with wasps naturalists have 
definitely stated that the birds begin to build close to the already con- 
structed pendent comb of a wasp, while their nests are actually excavated 
in the termite-mounds and in the huge nests of tree-ants. This most 
interesting and significant behaviour has been summarised for tropical 
America by J. G. Myers, who has confirmed the older records by his own 
observations and has also been led to the startling conclusion that at 
least one wasp tends regularly to make its nest beside the colonies of a 
tree-ant (Azteca). Notes on these associations in Africa have been 
written by A. Loveridge and V. G. L. van Someren; in India by E. C. 
Stuart Baker; in Australia by W. B. Alexander.** 
The behaviour briefly described in the last two paragraphs proves, I 
believe, that birds possess a brain and sense-organs such as would lead 
them, in seeking their food, to associate the qualities, favourable or un- 
favourable, with the appearance, and to remember and apply their 
experience, in fact precisely the powers required by a selective agent in 
building up a mimetic pattern. 
To the above evidence may be added two examples of bird behaviour 
in our own country. The cocoon of the common ‘Lackey Moth’ is 
thick on the exposed surface but thin where it is spun on to a leaf. Birds 
have discovered this and peck a hole through the leaf and thin wall in 
order to abstract the chrysalis.** Many naturalists have observed that 
birds, although they frequently peck their way into the centre of ‘ bullet- 
galls’ (often but erroneously called ‘ oak-apples’), never do so when the 
enclosed insect has emerged, being doubtless guided by the sight of the 
small round hole or by tapping with the bill.57 
What other hypotheses have been suggested by those who reject 
evolution by Natural Selection as the explanation of mimicry and allied 
adaptations? Some naturalists believe that the resemblances in question 
are accidental and of no biological significance. This opinion, although 
defended by such an eminent entomologist as Prof. Handlirsch,®* is not 
likely to be held by anyone who has seriously considered examples such 
as those brought before you to-day, or has studied the geographical 
distribution of mimetic associations. Chance resemblances are, of course, 
bound to occur among the immense number of butterfly patterns through- 
out the world, but these will be as frequently found between the species of 
different countries as between those of the same country. Such truly 
chance likenesses in patterns have been examined by my friend, Dr. F. A. 
_ Dixey,®® and have been shown to be relatively few and only to exist at all 
* Proc. Ent. Soc. Lond., vol. iv., 1929, p. 80 (America) ; p. 88 (Africa); p. 89 
(India) ; vol. v., 1930, p. 111 (Australia) ; vol. vi., 1931, p. 34 (India). 
°© Observed by A. H. Hamm. Jbid., 1902, p- Xv. 
*T Ibid., vol. iii., 1928, p- 50; vol. iv., 1929, p. 10. 
S Handbuch der Entomologie. 
® Proc. Ent. Soc. Lond., 1913, p. 1x. As regards chance likeness in form, Bates 
wrote in his great paper (p. 514 n.): ‘Some orders of insects contain an almost 
infinite variety of forms, and it will not be wonderful, therefore, if species here and 
