202 BIOLOGY AND ITS MAKERS 
nate in eggs, and it was directed against certain contrary 
medical theories of the time. 
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 ‘ev ovo omnia,’ and from the box issue all forms 
of living creatures, including also man. 
Malpighi.—The observer in cmbryology 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 devclopment are in two separate 
memoirs, both sent to the Royal Socicty in 1672, and pub- 
lished 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, repre- 
sent what he was able to sec, and are very remarkable for 
the age in which they were made, and considering the instru- 
ments of observation at his command. ‘They show successive 
stages from the time the embryo is first outlined, and, taken 
in their entircty, they cover a wide range of stages. 
His observations on the development of the heart, com- 
prising twenty figures, are the most complete. He clearly 
illustrates the aortic arches, those transitory structures of 
such great intcrest as showing a phase in ancestral history. 
He was also the first to show by pictures the formation of 
the head-fold and the neural groove, as well as the brain- 
