The generation of seeds...is therefore marvelous and analogous to the other productions of living things. For first of all an umbilicus appears...Its extremity gradually expands and after gathering a colliquamentous ichor becomes analogous to an amnion...In the course of time the seed or fetus begins to become visible.

'On the Developmental Process', in H. B. Adelmann (ed.), Marcello Malpighi and the Evolution of Embryology (1966), Vol. 2