The first edition of his Generatione Animalium, London, 1651, is provided with an allegorical frontispiece embodying this idea. As shown in Fig. 60, it represents Jove on a pedestal, uncovering a round box, or ovum, bearing the inscription "ex ovo omnia," and from the box issue all forms of living creatures, including also man.
Malpighi.—The observer in embryology who looms into prominence between Harvey and Wolff is Malpighi. He supplied what was greatly needed at the time—an illustrated account of the actual stages in the development of the chick from the end of the first day to hatching, shorn of verbose references and speculations.
His observations on development are in two separate memoirs, both sent to the Royal Society in 1672, and published by the Society in Latin, under the titles De Formatione Pulli in Ovo and De Ovo Incubato. The two taken together are illustrated by twelve plates containing eighty-six figures, and the twenty-two quarto pages of text are nearly all devoted to descriptions, a marked contrast to the 350 pages of Harvey unprovided with illustrations.
His pictures, although not correct in all particulars, represent what he was able to see, and are very remarkable for the age in which they were made, and considering the instruments of observation at his command. They show successive stages from the time the embryo is first outlined, and, taken in their entirety, they cover a wide range of stages.
His observations on the development of the heart, comprising twenty figures, are the most complete. He clearly illustrates the aortic arches, those transitory structures of such great interest as showing a phase in ancestral history.
Fig. 61.—Selected Sketches from Malpighi's Works. Showing Stages in the Development of the Chick (1672).
He was also the first to show by pictures the formation of the head-fold and the neural groove, as well as the brain-vesicles and eye-pockets. His delineation of heart, brain, and eye-vesicles are far ahead of those illustrating Wolff's Theoria Generationis, made nearly a hundred years later.
Fig. 61 shows a few selected sketches from the various plates of his embryological treatises, to compare with those of Wolff. (See Fig. 63.)