(loa EL > } 
XVIII. Lxperiments in 1893, 1894, and 1896 upon the 
colour-relation between lepidopterous larve and 
their surroundings, and especially the effect of 
lichen-covered bark upon Odontopera bidentata, 
Gastropacha quercifolia, etc. By Epwarp B. 
Pou.ton, D.Sc., M.A., LL.D. (Princeton), F.R.S., 
‘etc., Hope Professor of Zoology in the Univer- 
sity of Oxford, Fellow of Jesus College, Oxford. 
[Read June 3rd, 1903. ] 
Prates XVI, XVII, anp XVIII. 
THE circumstances under which the experiments re- 
corded in the present memoir were undertaken, afford a 
good example of the stimulus and encouragement to work 
rendered possible by that mutual intercourse and exchange 
of experience and ideas which are promoted by meetings 
of scientific societies. 
In the year 1892 I conducted an extensive series of 
experiments upon the adjustment of the colours of the 
larvee of Amphidasis betularia to those of their environ- 
ment (Trans. Ent. Soc. Lond., 1892, pp. 337-369). Living 
examples of the chief results obtained were shown at the 
meeting of Section D of the British Association at Edin- 
burgh, on August 9th (Report of the 1892 Meeting, p. 
786, where however the word “pup” is erroneously 
printed instead of “larve”). After the larve had been 
exhibited, Dr. Stacey Wilson, of Birmingham, asked if I 
had tried the effect of lichen-covered bark. Dr. Wilson 
stated that he had once beaten the larva from a food- 
plant with twigs covered by lichen, and that its appear- 
ance was entirely different from that usually borne by 
betularia. He looked upon it, in fact, as the larva of 
some other species, and was only convinced by breeding 
the moth (Trans. Ent. Soc. Lond., 1892, p. 360). The 
idea of making use of an environment of lichen-covered 
bark had not occurred to me, and I determined to try 
TRANS. ENT. SOC. LOND. 1903.—PART III. (OCT.) 21* 
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