AN INTRODUCTION TO THE STUDY OF ZOOLOGY, ILLUSTRATED BY THE CRAYFISH. BY T. H. HUXLEY, F. R. S. WITH EIGHTY-TWO ILLUSTRATIONS. NEW YORK AND LONDON D. APPLETON AND COMPANY 1920 144 D3 149 1920 56923 Filian Horsford Farlow Fund. Διὸ δεῖ μὴ δυσχεραίνειν παιδικῶς τὴν περὶ τῶν ἀτιμοτέρων ζῴων ἐπίσκεψιν· ἐν πᾶσι γάρ τοῖς φυσικοῖς ἕνεστί τι θαυμαστόν.”—ARISTOTLE, De Partibus, I. 5. "Qui enim Autorum verba legentes, rerum ipsarum imagines (eorum verbis comprehensa) sensibus propriis non abstrahunt, hi non veras Ideas, sed falsa Idola et phantasmata inania mente concipiunt. ...... "Insusurro itaque in aurem tibi (amice Lector!) ut quæcunque à nobis in hisce .... exercitationibus tractabuntur, ad exactam experientiæ trutinam pensites: fidemque iis non aliter adhibeas, nisi quatenus eadem indubitato sensuum testimonio firmissime stab liri deprehenderis."-HARVEY. Exercitationes de Generatione. Præfatio. "La seule et vraie Science est la connaissance des faits: l'esprit ne peut pas y suppléer et les faits sont dans les sciences ce qu'est l'expérience dans la vie civile." "Le seul et le vrai moyen d'avancer la science est de travailler à la description et à l'histoire des differentes choses qui en font l'objet.". BUFFON. Discours de la manière d'étudier et de traiter l'Histoire Naturelle. "Ebenso hat mich auch die genäuere Untersuchung unsers Krebses gelehret, dass, 80 gemein und geringschätzig solcher auch den meisten zu seyn scheinet, sich an selbigem doch so viel Wunderbares findet, dass es auch den grossten Naturforscher schwer fallen sollte solches alles deutlich zu beschreiben."-ROESEL V. ROSENHOF. Insecten Belustigungen.-"Der Flusskrebs hiesiges Landes mit seinen merkwurdigen Eigenschaften." CABOT SCIENCE LIBRARY -59/5.3 ૩ PREFACE. In writing this book about Crayfishes it has not been my intention to compose a zoological monograph on that group of animals. Such a work, to be worthy of the name, would require the devotion of years of patient study to a mass of materials collected from many parts of the world. Nor has it been my ambition to write a treatise upon our English crayfish, which should in any way provoke comparison with the memorable labours of Lyonet, Bojanus, or Strauss Durckheim, upon the willow caterpillar, the tortoise, and the cockchafer. What I have had in view is a much humbler, though perhaps, in the present state of science, not less useful object. I have desired, in fact, to show how the careful study of one of the commonest and most insignificant of animals, leads us, step by step, from every-day knowledge to the widest generalizations and the most difficult problems of zoology; and, indeed, of biological science in general. It is for this reason that I have termed the book an "Introduction to Zoology." For, whoever will follow its pages, crayfish in hand, and will try to verify for himself the statements which it contains, will find himself brought face to face with all the great zoological questions which excite so lively an interest at the present day; he will understand the method by which alone we can hope to attain to satisfactory answers of these questions; and, finally, he will appreciate the justice of Diderot's remark, "Il faut être profond dans l'art ou dans la science pour en bien posséder les éléments." And these benefits will accrue to the student whatever shortcomings and errors in the work itself may be made apparent by the process of verification. "Common and lowly as most may think the crayfish," well says Roesel von Rosenhof, "it is yet so full of wonders that the greatest naturalist may be puzzled to give a clear account of it." But only |