xxviii MEMOIRS, ETC., REFERRED TO. Rabl-Rückhard, Entw. des Knochenfischgehirns, Sitz. nat. urf. Freunde. Berlin 1882. Ranke, Beit. zur Lehre von den Uebergangs-Sinnesorganen, Zeit. für Wiss. Zool., 1875. Réaumur, Mém. p. servir à l'Histoire des Insectes. Report on the Locust Campaign, Parl. Paper, 5250 of 1888. Roesel, Insectenbelustigungen. Romanes, Mental Evolution in Animals. Animal Intelligence. Sars, On the Schizopoda, Challenger Reports, vol. xiii. Sazepin, Ueber den histol. Bau und die Vert. der nervösen Eudorgane auf den Fühlern der Myriopoden, Mém. de l'Acad. Imper. de St. Petersbourg, 1884. Schiemenz, Ueber das Vorkommen des Futtersaftes, etc., der Biene, Dissertation der Univ. Leipzig: 1883. Schmidt, Die Gehörorgane der Heuschrecken, Arch. für Mic. Anat., 1875. Die Stäbchen in der Retina der Cephalopoden und Heteropoden, Zur Anat. und Phys. der Retina, Arch. für Mic. Anat., 1866. Neue Beit. zur Anat. und Phys. der Retina, Arch. fur Mic. Anat., T. E., Ueber die Sinnesorgane der Seitenlinie bei Fischen und Semper, Ueber Schneken Augen am Wirbelthier Typus, Arch. für Mic. Serres, Marcel de, De l'odorat et des organes qui paraissent en être le siège chez les orthoptères, Annales du Muséum, 1811. Siebold, Ueber die Stimm und Gehörorgane der Krebse und Insekten, Arch. für Mic. Anat., 1860. Simroth, Ueber die Sinneswerkzeuge unserer einheimischen Weichthiere, Zeit. für Wiss. Zool., 1876. Slater, Ueber die Funktion der Antennen bei den Insekten, Froriep's Notizen, iii., 1848. Spencer, The Pineal Eye in Lacertilia, Quarterly Journal of Microscopical Science, 1886. Stricker, Manual of Histology. Sulzer, Geschichte der Insekten. 1761. MEMOIRS, ETC., REFERRED TO. Treviranus, Verm. Schriften Anat. und Physiol. Inhaltes, 1817. xxix Ussow, Ueber den Bau der sogenannten augenähnlichen Flecken einiger Knochenfische, Bull. S.c. Imp. Moscow, 1879. Valentine, R., and T. T. Cunningham, "The Photospheria of Nyctiphanes Norvegica," in Quarterly Journal of Microscopical Science, 1888. Vedjdovsky, Syst. und Morph. der Oligochoeten. 1884. Wagner, Untersuchungen über die zusammengesetzten Augen der Krebse und Insekten. 1868. Weissman, A., Die nachembryonale Entwicklung der Musciden, Zeit. für Wiss. Zool., 1864. Westwood, Modern Classification of Insects. Will, F., Ueber die Augen der Bivalven und der Acidien, Froriep's neue Notizen aus dem Gebiete der Nat. und Heilkunde, 1844. Das Geschmacksorgan der Insecten, Zeit. für Wiss. Zool., 1885. Wilson, The Nervous System of the Asterida, with Observations on the Structure of their Organs of Sense, Trans. Linn. Soc., 1860. Wolff, O. J. B., Das Riechorgan der Biene, Nova acta der K. L., Arch. deutsch. Akad. d. Naturf., 1875. ON THE SENSES, INSTINCTS, AND INTELLIGENCE OF ANIMALS. CHAPTER I. INTRODUCTORY REMARKS. THE organs of sense may be said to be the windows through which we look out into the world, and it has always been to my mind one of the most interesting problems of natural history, to consider in what manner external objects affect other animals, how far their perceptions resemble ours, whether they have sensations which we do not possess, and how we ourselves arrive at our own perceptions. I propose to dwell in the present work especially on the senses of insects, partly because my own observations have been made principally on them, and partly because their senses have, perhaps, been on the whole more thoroughly and successfully studied than those of the other lower animals; which again arises from the fact that no group offers more favourable opportunities for the study of these organs. The subject is no less vast than difficult, and I do not pretend in any way to give a complete view of the whole question, 39 B 2 DIFFICULTY OF THE SUBJECT. but have selected those cases which seemed to me the most suggestive, interesting, and instructive. No one can doubt that the sensations of other animals differ in many ways from ours. Their organs are sometimes constructed on different principles, and situated in very unexpected places. There are animals which have eyes on their backs, ears in their legs, and sing through their sides. Nevertheless, in considering the different senses, it will probably be most convenient to begin by a short summary of our own organs, as affording the best clue to the purposes and functions of corresponding structures among the lower animals. The subject is one of very great difficulty. Even as regards our own senses, we are still in extreme ignorance. The clue afforded by anatomy is very imperfect, and sometimes almost misleading. No one can read the literature relating to the organs of sense without feeling how very little we really know on the subject. Even when, as especially in the cases of the organs of hearing and sight, we have careful and elaborate descriptions and figures of very complex structures, these relate rather to the separation and arrangement of the waves of sound or light, than to the actual manner in which they affect the nervous system itself; while as to the manner in which our perceptions are in turn created, we are almost absolutely ignorant. In the senses of taste and smell this becomes, perhaps, even more clearly evident. Every cell, indeed, in the animal body is a standing miracle. Consider what it has to do. It must grow; it must assimilate nourishment; it must secrete; it must produce other cells like itself; and this often in addition to its own proper and distinctive function. The lowest animals consist but of a single cell. Yet they feed and |