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D.—ZOOLOGY. 91 
The second series of observations is now being undertaken at Vineyard 
Haven, Massachusetts, by Dr. Frank Morton Jones, who has kindly 
written to me, explaining the details of the excellent methods he is 
employing. Insects, chiefly Lepidoptera and Coleoptera, of known species 
are exposed on a feeding-tray in a favourable locality and the visits of 
birds watched at a distance through field-glasses. Thus on June 27 last, 
of 63 beetles belonging to 9 species placed on the tray, there remained in 
30 minutes, after 22 bird-visits (3 species), 15 beetles of one red-and-black 
species. Thus 48 beetles of 8 species were taken and all the 15 of the 
ninth species were untouched. Dr. F. M. Jones is also attempting to form 
a scale of distastefulness by observing the reactions of a common species 
of ant to the insects employed in the experiments. 
One of the chief criticisms made by McAtee and made in this country 
also, was the insufficiency of the evidence that butterflies are commonly 
attacked by birds, the enemies believed to be the selective agents in the 
evolution of mimicry. McAtee, in support of this objection, quoted the 
results of an American agricultural investigation in which an enormous 
number of birds’ stomachs had been examined and remains of butterflies 
found in only an insignificant proportion. This criticism had been in 
great part met beforehand in a paper ‘*® published by Sir Guy Marshall in 
1909; and more recently C. F. M. Swynnerton*® and W. A. Lamborn®® 
have conclusively shown that butterflies are rapidly reduced to such 
minute fragments in a bird’s digestive tract that examination with the 
compound microscope is necessary in order to obtain trustworthy results. 
Furthermore, it is only in recent years that the imprint of a bird’s beak 
on a butterfly’s wing has been noticed ; but now that attention has been 
directed to this evidence it is found to be quite common—a good example 
of the fertile but, for the uncritical, the dangerous principle that an 
observer only finds what he looks for. 
It is possible that the mistaken assumption of the immunity of models 
has played a part in prompting Dr. Bequaert’s interesting paper on the 
enemies of ants.54 Admitting the existence of these enemies and the 
certainty that the list will be immensely lengthened, it still remains that 
ants are ‘the most powerful of insects, ever-present and aggressive in all 
habitable parts of the earth.’®? And it is difficult to reconcile with Dr. 
Bequaert’s opinion that they are valueless as models, the fact that my friend 
Mr. H. St. J. K. Donisthorpe has, since 1891, discovered, in the nests of 
British ants, ‘ 204 species of insects, spiders and mites new to the country, 
including 74 new to science. Of these guests 28 are mimics of ants... . 
He has also recorded 34 mimics living independently of ants.’5* I believe 
that most naturalists will conclude from these discoveries in Great Britain 
and Ireland, and from the remarkable profusion of ant-mimics and ant- 
48 Trans. Ent. Soc. Lond., 1909, p. 329. See especially pp. 336, 337. 
49 Linn. Soc. Journ. Zool., xxiii., 1919, p. 203. Abstract in Proc. Ent. Soc. Lond., 
1915, p. xxxii. 
50 Proc. Ent. Soc. Lond., 1920, p. xxvi. 
5! Bull. Am. Mus. Nat. Hist., vol. xlv., p. 271, New York, 1922. 
52 Zoolog. Anz. (Wasmann-Festband), 1929, p. 86. 
58 Ibid., p. 84. Quoted from ‘ Guests of British Ants,’ Donisthorpe, London, 1927. 
The numbers have been brought up to date with the kind help of the author. 
