—— On the eyes of molluscs and arthropods. (Zool. Anzeiger, 1887, x Jahrg., pp. 256–261.) —— Is the ommatidium a hair-bearing sense-bud? (Anatom. Anzeiger, 1890, v, pp. 353–359, 4 Figs.) =Exner, S.= Ueber das Sehen von Bewegungen und die Theorie des zusammengesetzten Auges. (Sitzgsber. d. math. naturwiss. Cl. kais. Akad. d. Wissens. Wien, lxxii Jahrg., 1875, 3 Abt. Physiologie, pp. 156–190, 1 Taf.) —— Die Frage von der Funktionsweise der Fazettenauges. (Biolog. Centralblatt, i, 1881, pp. 272–281.) —— Das Netzhautbild des Insektenauges. (Sitzgsber. kais. Akad. d. Wissensch. Wien, 1889, xcviii, 3 Abt., pp. 13–65, 2 Taf. u. 7 Figs.) —— Durch Licht bedingte Verschiebungen des Pigmentes im Insektenauge und deren physiologische Bedeutung. (Ibid., pp. 143–151, 1 Taf.) =Exner, S.= Die Physiologie der fazettierten Augen von Krebsen und Insekten, 7 Taf., 1, Lichtdruck u. 23 Holzschn. pp. 206. Wien, F. Deuticke, 1891. =Lubbock, John.= On the senses, instincts, and intelligence of animals, with special reference to insects. London, 1888, pp. 292. =Mallock, A.= Insect sight and the defining power of composite eyes. (Proc. Roy. Soc., London, 1894, lv, pp. 85–90, 3 Figs.) _b_. The color-sense =Nussli, J.= Ueber den Farbensinn der Bienen. (Schweiz. Bienenzeitung, N. F., ii Jahrg., 1879, pp. 238–240.) =Kramer.= Der Farbensinn der Bienen. (Ibid., iii Jahrg., 1880, pp. 179–198.) =Gross, Wilhelm.= Ueber den Farbensinn der Tiere, insbesondere der Insekten. (Isis v. Russ., v Jahrg., 1880, pp. 292–294, 300–302, 308–309.) =Lubbock, John.= Ants, bees, and wasps. London, 1882, pp. 448. Also On the senses, etc., of animals, 1889. =Graber, Vitus.= Grundlinien zur Erforschung des Helligkeits und Farbensinnes der Tiere. Prag u. Leipzig, 1884, pp. 322. (See also p. 262.) =Forel, Auguste.= Les Fourmis perçoisent-elles l’ultra-violet avec leurs yeux ou avec leur peau? (Arch. Sci. Phys. Nat. Genève, 1886, 3 sér., xvi, pp. 346–350.) Also the works of Darwin, Wallace, F. Müller, Grant Allen’s The Color Sense (1879), Beddard’s Animal Coloration, etc. _b_. The organs of smell The seat of the organs of smell is mainly in the antennæ, and they may be regarded as the principal olfactory organs. For our present knowledge of the anatomy and physiology of the olfactory organs of insects we are mainly indebted to the recent investigations of Hauser and of Kraepelin. The following historical and critical remarks are translated from Kraepelin’s able treatise: =Historical sketch of our knowledge of the organs of smell.=—In the first half of the last century began the inquiries as to the seat of the sense of smell in the arthropods. Thus Réaumur, in his Mémoires (i, p. 283; ii, 224), expressed the view that in the antennæ was situated a special organ which might be an organ of smell.