HEREDITARY INFLUENCE. 
717 
mal in miniature. The early microscopists observing the 
gradual appearance of the organs, jumped to the conclusion 
that the organs pre-existed in the ovum, and were gradually 
unfolded to view as they became larger. Indeed, when we 
see an egg by no means increased, either in size or weight, 
suddenly open, and a full-formed chick emerge, the idea that 
the chick was pre-existent in that liquid mass which once 
constituted the egg, seems plausible enough. Swammer- 
dam and Malebranche pushed this notion to its logical con- 
clusion, and declared that not only was the embryo a 
miniature of the adult, but the first created embryo of each 
species necessarily contained within itself all the germs of 
the future race ; so that each generation included all sub- 
sequent generations. This is the famous theorie de Vemboite- 
ment , which was advocated even by Cuvier That Bonnet, 
Haller, and lesser men, should have been seduced by such a 
theory, is not remarkable when we consider the state of 
knowledge in their days; but after C. F. Wolff, Blumenbach, 
and Yon Baer, had utterly refuted it, and replaced it by the 
sounder theory of epigenesis, to find Cuvier still giving it 
the sanction of his great name, is a point to be remembered 
in the history of opinion. At the present day, we believe no 
one of any authority maintains the theory of pre-existence. 
The microscope plainly shows us that, at first, the embryo is 
not like the adult animal in any respect; the resemblance 
grows as development goes on ; the presence of one organ 
determines the presence of another; and, in the earlier 
stages, we cannot tell whether the embryo is that of a fish, a 
reptile, a bird, or a mammal, much less what kind of fish, 
reptile, bird, or mammal. It is the immortal honour of 
C. F. Wolff to have demonstrated the great law of epige- 
nesis,* by which the parts of an animal are made one after 
another, and out of the other; so that each organ may be 
considered as a secreting organ with respect to the others. 
Treviranus subsequently adopted this idea of each organ 
having, as it were, a secretory function with respect to the 
others ; and Mr. Paget has luminously expanded it in his 
masterly ‘ Lectures on Surgical Pathology.’ 
When it was believed that animals pre-existed in the germs 
of the original parents, the difficulty of accounting for varia- 
tions, such as deformities and malformations, was either 
ignored, referred to u Satanic agency,” or eluded by the 
* ‘Theoria Generationis.’ 1759 ; and in a more popular version of the 
same work, ‘ f heorie von der Generation.’ We have never seen the first- 
named work ; the second we can commend to philosophic readers. 
