In the same way we are in entire ignorance as to the physical mechanism of ontogenetic development, the evolution of the embryo.
"The Mechanism of Life"
Stéphane Leduc
Variations and heredity are generally estimated, not according to the inner nature of the mature individuals, but according to their relation in successive generations, since heredity is assumed when the ontogenetic characters remain the same, and variation when previously latent characters become visible.
"A Mechanico-Physiological Theory of Organic Evolution"
Carl Von Nägeli
This is perceived from the succession of the visible ontogenetic characteristics which in general run parallel with it.
"A Mechanico-Physiological Theory of Organic Evolution"
Carl Von Nägeli