cenogenetic

On the other hand, this is certainly not the case with the following embryonic forms, which we must describe as cenogenetic processes: the formation of the yelk-sac, the allantois, the placenta, the amnion, the serolemma, and the chorion -- or, generally speaking, the various foetal membranes and the corresponding changes in the blood vessels.

The Evolution of Man — Volume 1 Ernst Heinrich Philipp August Haeckel 1876

In all other extent Vertebrates these fundamental processes have been more or less modified by adaptation to the conditions of embryonic development especially by changes in the food yolk; they exhibit various cenogenetic forms of the formations of the germlayers, and thus develop by means of a metagastrula.

Haeckel on gastrulation - The Panda's Thumb 2006

This typical formation might be masked by cenogenetic modifications caused chiefly by the presence of yolk.

Form and Function A Contribution to the History of Animal Morphology

Gastræa theory (1875), [378] he had to work out a distinction between palingenetic and cenogenetic characters, of which much use was made by subsequent writers.

Form and Function A Contribution to the History of Animal Morphology

It is worthy of note that the help of comparative anatomy is admittedly required in deciding what processes are palingenetic and what cenogenetic (p. 412).

Form and Function A Contribution to the History of Animal Morphology

The cenogenetic phenomena, on the other hand, or the embryonic _variations_, cannot be traced to inheritance from a mature ancestor, but are due to the adaption of the embryo or the larva to certain conditions of its individual development (e.g. the amnion, the allantois, and the vitelline arteries in the embryos of the higher vertebrates).

Evolution in Modern Thought Gustav Schwalbe 1880

When these coelom-embryos develop, not as a pair of hollow pouches, but as solid layers of cells (in the shape of a pair of mesodermal streaks) -- as happens in the higher vertebrates -- we have a secondary (cenogenetic) modification of the primary (palingenetic) structure; the two walls of the pouches, inner and outer, have been pressed together by the expansion of the large food-yelk.

The Evolution of Man — Volume 1 Ernst Heinrich Philipp August Haeckel 1876

The cenogenetic modifications of the latter are more appreciable the more food-yelk is stored up in the ovum.

The Evolution of Man — Volume 1 Ernst Heinrich Philipp August Haeckel 1876

These cenogenetic modifications seem to be so great that until twenty years ago these important processes were totally misunderstood.

The Evolution of Man — Volume 1 Ernst Heinrich Philipp August Haeckel 1876

Moreover, in the animals in which we do not find a real palingenetic blastula the defect is clearly due to cenogenetic causes, such as the formation of food-yelk and other embryonic adaptations.

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876