IN DEFENSIVE COLORATION 307 



The experiment was then tried, with equally successful 

 results, upon the young larvae of Gastropacha quercifoLia 

 (the Lappet Moth). In this case the change was pro- 

 duced before hybernation, and no subsequent change in 

 the conditions availed to effect any modification. The 

 appearance of bark densely covered by masses of grey 

 lichen was beautifully reproduced on some of the larvae, 

 and considerable effects were wrought in all exposed to 

 the above-named conditions. 



In these experiments, as in all others of the kind, the 

 effects produced are those with which the field naturalist 

 is perfectly familiar. The advance in our knowledge 

 consists in the proof that such familiar effects are con- 

 trollable, and in ascertaining the conditions under which 

 they are evoked. 



Adjustable Protective Resemblance, probably of an 

 analogous kind, is known in Coleoptera. Thus Mr. W. 

 Holland ^ has observed that the specimens of a well- 

 known British weevil, Cleomis stilcirostris, are reddish- 

 brown upon the sands of Boar's Hill, near Oxford, dark 

 grey on Shotover Hill, also near Oxford, and a pale 

 grey on the Deal sand-hills. I also observed in 1901 

 that the very abundant individuals of a species of grass- 

 hopper in Heligoland were invariably dark reddish brown 

 like the earth, while on the flat sandy Dime, three- 

 quarters of a mile away by sea, they were sand- 

 coloured, or, more rarely, green like the grass. It is 

 probable that experiment would prove that many such 

 Coleoptera and Orthoptera, as well as the flower-haunting 

 spiders, possess a power of individual colour-adjustment 

 similar to that proved to exist in many Lepidopterous 

 larvae and pupae. The alternative interpretation sug- 

 gested in the next Section is probably inapplicable 

 here. 



II. Coincidence betiveen the Colours of Organisms and 

 those of their Peculiar Efivironments may be probably 

 Caused by the Local Operation of Natural Selection, — 

 It is well known that individuals of the Geometrid moth 

 Gnophos obscurata are light-coloured when found upon 



* Trans, Ent. Soc, Lond., 1899, p. 430. 



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