The experimental study of form was prosecuted in many other directions besides that of experimental embryology. The study of regeneration and of regulatory processes attracted many workers, among whom may be mentioned T. H. Morgan, C. M. Child, and H. Driesch. In an interesting series of papers C. Herbst applied the principles of the physiology of stimulus to the interpretation of development.[505] The formative power of function was studied in Germany by Roux and his pupils, Fuld, O. Levy, Schepelmann and others, particularly by E. Babak. In France, F. Houssay inaugurated[506] an important series of memoirs by himself and his pupils on "dynamical morphology," the most important memoir being his own valuable discussion of the functional significance of form in fishes.[507] The principles of his dynamical morphology were first laid down in his book _La Forme et la Vie_ (1900). The famous experiments of Loeb, Delage and others on artificial parthenogenesis may also be mentioned, though their connection with morphology is somewhat remote. The period was characterised also by the lively discussion of first principles, in which Driesch took a leading part. Materialistic methods of interpretation were upheld by perhaps the majority of biologists, but vitalism found powerful support. [464] See Carus's remark, referred to on p. 194, above. [465] Roux, _Die Entwicklungsmechanik_, p. 26, Leipzig, 1905. [466] T. H. Morgan, _Regeneration_, p. 1, New York and London, 1901. [467] _Recherches sur la production artificielle des Monstruosites_, Paris, 1877, and many later papers. [468] _Unsere Koerperform und das physiologische Problem ihrer Entstehung_, Leipzig, 1874. [469] J. W. Jenkinson, _Experimental Embryology_, p. 3, Oxford, 1909. [470] "Ueber die Verzweigungen der Blutgefaesse des Menschen," _Jen. Zeit_., xii., 1878. [471] "Ueber die Bedeutung der Ablenkung des Arterienstammes bei der Astabgabe," _Jen. Zeit_., xiii., 1879. [472] "Beitraege zur Morphologie der funktionellen Anpassung. I. Struktur eines hochdifferenzierten bindgewebigen Organes (der Schwanzflosse des Delphin)," _Arch. Anat. Physiol._ (_Anat. Abt._) for 1883. II. "Ueber die Selbstregulation der 'morphologischen' Laenge der Skeletmuskeln des Menschen," _Jen. Zeit._, xvi., 1883. III. "Beschreibung ... einer Kniegelenkeknochenankylose," _Arch. Anat. Physiol._ (_Anat. Abt._) for 1885. [473] In 1869 and 1877 respectively (Roux, p. 53, 1905). [474] _Ueber die Zeit. der Bestimmung der Hauptrichtungen des Froschembryo_, Leipzig, 1883. [475] "Ueber den Einfluss der Schwerkraft auf die Teilung der Zellen," Pflueger's _Archiv_, xxxi., 1883. Also subsequent papers in same journal. [476] For an account of the classical experiments on the frog's egg, see T. H. Morgan, _The Development of the Frog's Egg_, New York, 1897.