[526] "La Pœcilogonie," Bull. Sci. France et Belgique, xxxix., pp. 153-87, 1905.

[527] Un problème de l'évolution. La loi biogénétique fondamentale, Paris and Montpellier, 1908.

[528] Vergleichung des Entwickelungsgrades der Organe zu verschiedenen Entwickelungszeiten bei Wirbeltieren, Jena, 1891.

[529] Quoted by Keibel, Ergebn. Anat. Entwick., vii., p. 741.

[530] "Studien zur Entwickelungsgeschichte des Schweines," Schwalbe's Morphol. Arbeiten, iii., 1893, and v., 1895.

Normentafeln zur Entwickelungsgeschichte des Schweines, Jena, 1897.

"Das biogenetische Grundgesetz und die Cenogenese," Ergebn. Anat. Entw., vii., pp. 722-92, 1897.

"U. d. Entwickelungsgrad der Organe," Handb. vergl. exper. Entwick. der Wirbelthiere, iii., 3, pp. 131-48, 1906.

[531] "Beiträge zur Embryologie der Wiederkäuer," Arch. Anat. Entw., 1889.

[532] "Die individ. Variation d. Wirbeltierembryo," Morph. Arbeit., v., 1895.

[533] "U. Variabilität u. Wachstum d. embryonalen Körpers," Morph. Jahrb., xxiv., 1896.

[534] "Gastrulation u. Keimblätterbildung der Emys lutaria taurica," Morph. Arbeit., i., 1891. "Kainogenese," Morph. Arbeit., vii., pp. 1-156, 1897, and also separately. Biomechanik, erschlossen aus dem Prinzipe der Organogenese, Jena, 1898.

[535] This law was foreshadowed by Reichert in 1837, when he wrote:—"We notice in our investigation of embryos of different animal forms that it is those organs, those systems, which in the fully developed individual are peculiarly perfect, that in their earliest rudiments and also throughout the whole course of their development appear with the most striking distinctness" (Müller's Archiv, p. 135, 1837). See also his Entwick. Kopf. nackt. Amphib., p. 198, 1838. So, too, Rathke notes how the elongated shape of the snake appears even in very early embryonic stages (Entwick. Natter., p. 111, 1839).

[536] Quoted by Keibel (p. 790, 1897) from the Biomechanik.

[537] Die Zelle und die Gewebe, Jena, 1898, and the subsequent editions of this text-book, published under the title of Allgemeine Biologie. Die Entwickelung der Biologie im neunzehnten Jahrhundert, Jena, 1900, 2nd ed., 1908. "Ueber die Stellung der vergl. Entwickelungslehre zur vergl. Anatomie, zur Systematik und Descendenztheorie," Handb. vergl. exper. Entwickelungslehre der Wirbeltiere, iii., 3, pp. 149-80, Jena, 1906. (1906, b). Also in Pt. I. of Vol. I. (1906, a).

[538] An Essay on Classification, London, 1859.

[539] Unsere Körperform, Leipzig, 1874.

[540] Q.J.M.S., xxxvi., pp. 35-52, 1894.

[541] Quoted by Hertwig. See also K. Goebel, "Die Grundprobleme der heutigen Pflanzenmorphologie," Biol. Centrbl., xxv., pp. 65-83, 1905.

[542] This is also emphasised by Fleischmann in his critical study of evolutionary morphology entitled Die Descendenztheorie, Leipzig, 1901.

[543] The same remark applies to the bulk of speculation as to the factors of evolution, with the exception of the contributions made to evolution theory by the palæontologists by profession, such as Cope.

[544] Les Transformations du Monde animal, Paris, 1907.

[545] "Malacology versus Palæoconchology," Proc. Malacological Soc., viii., pp. 66-83, 1908.

[546] Particularly by E. Perrier, "La Tachygenèse," Ann. Sci. nat. (Zool.) (8), xvi., 1903.

[547] Monatsber. k. Akad. Wiss., Berlin, pp. 474-504, 1866.

[548] Geognost. u. Palæont. Beiträge, ii., Heft 2, pp. 181-256, 1869.

[549] Abhand. k.k. Geol. Reichsanstalt, vii., Wien, 1875.

[550] The case for polyphyletism is very strongly put by G. Steinmann in his book, Die geologischen Grundlagen der Abstammungslehre, Leipzig, 1908.

[551] The steps in this chronological variation were termed by Waagen "mutations."

[552] The Age of Mammals in Europe, Asia, and North America, New York, 1910.

[553] Origin of Species, 6th ed., Chap. IV.

INDEX