[204]. Compare Brücke, ‘Farbenwechsel des Chamäleon.’ Wien. Sitzber. 1851. Also Leydig, ‘Die in Deutschland lebenden Saurier,’ 1872.
[205]. ‘Philosophical Transactions,’ vol. cxlviii. 1858, pp. 627-644.
[206]. Adler, ‘Beiträge zur Naturgeschichte der Cynipiden,’ Deutsche entom. Zeitschr. XXI., 1877, p. 209; and by the same author, ‘Ueber den Generationswechsel der Eichen-Gallwespen,’ Zeitschr. f. wiss. Zool., Bd. XXXV. 1880, p. 151.
[207]. Beyerinck, ‘Beobachtungen über die ersten Entwicklungsphasen einiger Cynipidengallen,’ Verhandl. d. Amsterd. Akad. d. Wiss. Bd. XXII. 1883.
[208]. l. c., p. 144.
[209]. [It is now known that many such caterpillars are actually modified in colour by their surroundings, but the process appears to be indirect and secondarily acquired by the operation of natural selection, like that of the change of colour in the chamaeleon, frogs, fish, etc.; although the stimulus of light acts upon the eyes of the latter animals and upon the skin of the caterpillar. See the seventh Essay (pp. 394-397) for a more detailed account.—E. B. P.]
[210]. l. c., p. 150.
[211]. In order to make the case as simple as possible, I assume that the insectivorous bird feeds upon a single species of insect, and that the insect is only attacked by a single species of bird.
[212]. English Edition, translated by D’Arcy W. Thompson, B.A. London, 1883, p. 509 et seqq.