(9) The animal is sensitive to touch over the whole surface of the body, but especially on the chelæ and chelipedes, the mouth-parts, the ventral surface of the abdomen, and the edge of the telson. If one side of the carapace or of the dorsal surface of the abdomen be stimulated, the extensors of the legs on the opposite side are contracted, and the animal turns on its antero-posterior axis toward the source of the stimulus. If opposite sides be stimulated alternately, a peculiar rolling motion is set up.
FOOTNOTES:
[1] Münsterberg: Perception of Distance, The Journal of Philosophy, Psychology and Scientific Methods, vol. 1, p. 617, 1904.
[2] E. Mach: Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1874.
[3] A. Crum Brown: Proceedings of the Royal Soc., Edinburgh, 1874.
[4] J. Breuer: Med. Jahrb., Wien, 1874-75.
[5] W. Peters: Arch. f. d. ges. Psych., vol. 5, p. 42, 1905.
[6] W. Nagel: Handbuch d. Physiol. des Menschen, vol. 3, p. 762, 1905.
[7] R. Dodge: Amer. Jour. of Physiol., vol. 8, p. 317, 1903.