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THE INFLUENCE OF DARWIN ON THE 
STUDY OF ANIMAL EMBRYOLOGY 
By A. Sepewick, M.A., F.R.S. 
Professor of Zoology and Comparative Anatomy in the 
University of Cambridge. 
THE publication of The Origin of Species ushered in a new era in 
the study of Embryology. Whereas, before the year 1859 the facts of 
anatomy and development were loosely held together by the theory 
of types, which owed its origin to the great anatomists of the pre- 
ceding generation, to Cuvier, L. Agassiz, J. Miiller, and R. Owen, 
they were now combined together into one organic whole by the 
theory of descent and by the hypothesis of recapitulation which was 
deduced from that theory. The view! that a knowledge of embryonic 
and larval histories would lay bare the secrets of race-history and 
enable the course of evolution to be traced, and so lead to the 
discovery of the natural system of classification, gave a powerful 
stimulus to morphological study in general and to embryological 
investigation in particular. In Darwin’s words: “Embryology rises 
greatly in interest, when we look at the embryo as a picture, 
more or less obscured, of the progenitor, either in its adult or larval 
state, of all the members of the same great class%” In the period 
under consideration the output of embryological work has been 
enormous. No group of the animal kingdom has escaped exhaustive 
examination and no effort has been spared to obtain the embryos of 
isolated and out of the way forms, the development of which might 
have an important bearing upon questions of phylogeny and classifi- 
cation. Marine zoological stations have been established, expeditions 
have been sent to distant countries, and the methods of investigation 
have been greatly improved. The result of this activity has been 
that the main features of the developmental history of all the most 
important animals are now known and the curiosity as to develop- 
mental processes, so greatly excited by the promulgation of the 
Darwinian theory, has to a considerable extent been satisfied. 
1 First clearly enunciated by Fritz Miiller in his well-known work, Fiir Darwin, 
Leipzig, 1864; (English Edition, Facts for Darwin, 1869). 
2 Origin (6th edit.), p. 396. 
