rative evidence of the
existence of cytoplasmic organ-forming stuffs has been supplied for
several other species, _e.g._, _Patella_ (Wilson), _Cynthia_ (Conklin),
_Cerebratulus_ (Zeleny), and _Echinus_ (Boveri).

It is interesting to recall that so long ago as 1874 W. His[504] put
forward the theory that there exist in the blastoderm and even in the
egg prelocalised areas, which contain the formative material for each
organ of the embryo, and from which the embryo is developed by a simple
process of unequal growth.

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 B