IV.
Biological Value of Colour, p. [289].
General prevalence of protective colouring among caterpillars, [289]. Polymorphic adaptive colouring in C. Elpenor, C. Porcellus, P. Œnotheræ, D. Vespertilio, D. Galii, D. Livornica, D. Hippophaës, [295]. Habit of concealment primary; its causes, [298]. Polymorphism does not here depend upon contemporaneous but upon successive double adaptation; displacement of the old by a new adaptation; proof in the cases of D. Hippophaës, D. Galii, D. Vespertilio, M. Stellatarum, C. Elpenor, and S. Convolvuli, [300].
V.
Biological Value of special Markings, p. [308].
Four chief forms of marking among Sphingidæ, [309]. Complete absence of marking among small caterpillars and among those living in obscurity, [310]. Longitudinal stripes among grass caterpillars, [312]. Oblique striping. Coloured edges are the shadows of leaf ribs, [317]. Eye-spots and ring-spots. Definition, [326]: Eye-spots not originally signs of distastefulness, [328]; they are means of alarm, [329]; experiments with birds, [330]; possibility of a later change of function in eye-spots, [334]. Ring-spots. Are they signs of distastefulness? Are there caterpillars which are edible and which possess bright colours? [335]; experiments with lizards, [336]. In D. Galii, D. Euphorbiæ, D. Dahlii and D. Mauritanica the ring-spots are probably signs of distastefulness, [341]. In D. Nicæa they are perhaps also means of exciting terror, [342]. The primary ring-spot in D. Hippophaës is a means of protection, [344]. Subordinate markings. Reticulation, [347]. The dorsal spots of C. Elpenor and C. Porcellus, [348]. The lateral dots of S. Convolvuli, [348]. Origination of subordinate markings by the blending of inherited but useless markings with new ones, [349].
VI.
Objections to a Phyletic Vital Force, p. [352].
Independent origination of ring-spots in species of the genus Deilephila, [352]. Possible genealogy of this genus, [358]. Independent origination of red spots in several species of Smerinthus, [360]. Functional change in the elements of marking, [365]. Colour change in the course of the ontogeny, [367].