History of Comparative Anatomy 339 



dermis, the " Malpighian corpuscles" in the kidney, and certain bodies 

 in the spleen. 



Embryology, even more important than histology as a working 

 ally of anatomy, had its beginnings in Aristotle, Fabricius, Harvey, 

 and Malpighi. The optical limitations of the early microscopes put 

 embryology temporarily on the wrong track. Malpighi, studying chick 

 embryos, concluded that most, if not all, of the organs of the adult must 

 be already present in a formed state in the unincubated egg. During 

 most of the eighteenth century, this idea of "performation," strongly 

 advocated by the naturalist Bonnet, the physiologist Haller, and the 

 philosopher Leibnitz, dominated embryology. Development con- 

 sisted essentially in mere enlargement of miniature organs preexisting 

 in the germ and then unfolding to view, somewhat as the bud of a 

 flower opens. The term "evolution," meaning literally an "unfolding," 

 was first applied to embryonic development as thus conceived. Harvey, 

 however, believed, as did Aristotle 20 centuries before him, that organs 

 develop — that is, gradually acquire form and structure — from an un- 

 formed germinal substance. To this method of development Harvey ap- 

 plied the name "epigenesis." Better microscopes enabled later embry- 

 ologists— notably C. F. Wolff (1733-94), J. F. Meckel (1781-1833), 

 and Karl E. von Baer (1792-1876) — to obtain positive proof that 

 development is epigenetic. 



THEORY OF EVOLUTION 



Comparative anatomy, established as a science by Aristotle and re- 

 vived after the Dark Ages by Vesalius, entered, at about the middle of 

 the eighteenth century, a period within which its point of view, pur- 

 poses, and methods were to undergo profound change. This period, 

 extending through the middle third of the nineteenth century, was 

 lighted by a brilliant constellation of names. First, in Sweden was the 

 naturalist Linnaeus (1707-78), and in France the philosopher and nat- 

 uralist Button (1707-88). Then in England appeared Erasmus Dar- 

 win (1731-1802), naturalist, philosopher, poet, and grandfather of 

 Charles Darwin. In France a little later were the philosophic naturalist 

 Lamarck (1744-1829), and Geoffroy Saint-Hilaire (1772-1844), a 

 philosophic comparative anatomist, and also Cuvier (1769-1832), per- 

 haps the most eminent of comparative anatomists, founder of Paleon- 

 tology, but little inclined toward speculative and philosophic thinking. 

 Meanwhile, in Germany was Goethe (1749-1832), sometimes bota- 

 nist and anatomist, sometimes poet, and always a philosopher. The 

 highly speculative ideas of Oken (1779-1851), another German, made a 

 temporary impress on anatomic science. 



Biologic knowledge in the eighteenth century comprised an exten- 

 sive volume of firmly established fact. The microscope had made highly 



