200 BIOLOGY AND ITS MAKERS 
the devclopment of the chick. Except the figures of Coiter 
(1573), those of Fabricius were the earliest published illus- 
trations of the kind. Altogether his figures show develop- 
mental stages of the cow, sheep, pig, galeus, serpent, rat, and 
chick. 
Harvev’s own treatise was not illustrated. With that 
singular independence of mind for which he was conspicuous, 
the vision of the pupil was not hampered by the authority of 
his teacher, and, trusting only to his own sure observation 
and reason, he described the stages of devclopment as he 
saw them in the egg, and placed his own construction on 
the facts. 
One of the earliest activities to arrest his attention in the 
chick was a pulsating point, the heart, and, from this observa- 
tion, he supposed that the heart and the blood were the first 
formations. He says: ‘But as soon as the egg, under the 
influence of the gentle warmth of the incubating hen, or of 
warmth derived from another source, begins to pullulate, 
this spot forthwith dilates, and expands like the pupil of the 
eye; and from thence, as the grand center of the egg, the 
latent plastic force breaks forth and germinates. This first 
commencement of the chick, however, so far as I am aware, 
has not yet been observed by any one.” 
It is to be understood, however, that the descriptive part 
of his treatise is relatively brief (about 40 pages out of 350 in 
Willis’s translation), and that the bulk of the 106 ‘ exercises” 
into which his work is divided is devoted to comments on the 
older writers and to discussions of the nature of the process 
of development. 
The aphorism, “ emie vivum ex ovo,” though not invented 
by Harvey, was brought into general use through his writings. 
As used in his day, however, it did not have its full modern 
significance. With Harvey it meant simply that the embryos 
of all animals, the viviparous as well as the oviparous, orig- 
