gametogenic

Adaptations are due to somatogenic modifications, non-adaptive diagnostic characters to gametogenic mutations.

Hormones and Heredity J. T. Cunningham 1897

For the present, therefore, we must conclude that feathers are not an adaptation, and not due to somatogenic modification, but must be result of a gametogenic mutation.

Hormones and Heredity J. T. Cunningham 1897

At the same time there are some somatic sex-characters, _e. g._ in insects and birds, which do not appear to be correlated with changes in the gonads, and which are probably gametogenic, not somatogenic in origin.

Hormones and Heredity J. T. Cunningham 1897

Most of the characters in domesticated varieties are obviously gametogenic mutations, but the lop-ear in rabbits may be, partly at least, somatogenic.

Hormones and Heredity J. T. Cunningham 1897

Finally it may be urged, although the question has not been directly discussed in this volume, that no biologist is justified in the present state of knowledge in dogmatically teaching the lay public that gametogenic characters are alone worthy of attention in questions of eugenics and sociology.

Hormones and Heredity J. T. Cunningham 1897

The author's view is that are two kinds of variation in evolution, one somatogenic and due to external stimuli, acting either directly on passive tissues or indirectly through function, and the other gametogenic and due to changes in the chromosomes of the gametes which are spontaneous and not in any way due to modifications of the soma.

Hormones and Heredity J. T. Cunningham 1897

The majority of evolutionists in recent years have taught that influences exerted through the soma have no effect on the determinants in the chromosomes of the gametes, that all hereditary variations are gametogenic and none somatogenic.

Hormones and Heredity J. T. Cunningham 1897

It has been the main argument of this volume that there are two distinct kinds of characters in all organisms -- namely, those of somatogenic origin and those of gametogenic origin.

Hormones and Heredity J. T. Cunningham 1897

But it is obvious that the black and white of Leghorn fowls and of guinea-pigs are gametogenic characters, and are strongly established in the gametes of their respective varieties.

Hormones and Heredity J. T. Cunningham 1897

No cases of mutation or gametogenic variation hitherto described exhibit a similar metamorphosis or recapitulation.

Hormones and Heredity J. T. Cunningham 1897