them the future organism is found in a ready strongly reduced state in
the cells (ovists in the eggs and spermatists — in the spermatozoa),
which later on undergoes its individual development. Extremal
preformists such as the Swiss philosopher and naturalist Charles Bonnet
were holding the view that in the embryo of the ovary is already
contained the embryo of the next generation, in it the next and so on.
image
Fig. 2–6. Schematic imaging of cell walls (After Link, 1807; From Katznelson, 1963).
A decisive rebuff to the preformists was rendered by the theory of
epigenesis. Its more well-known supporters are R. Descartes, D. Didrot,
C. F. Wolff, P. Maupertuis, W. Harvey, etc. On the basis of the epigenetic
concepts and insights of that time which have admitted formation and
development of the embryos, the studies on the cell are driven in the right
direction and the cell theory has been conceived.