parent-form

As a consequence of this the embryo, even when the parent-form undergoes a great amount of modification, is left only slightly modified; and the embryos of widely-different animals which are descended from a common progenitor remain in many important respects like each other and their common progenitor.

Haeckel on gastrulation - The Panda's Thumb 2006

At present I should prefer any mad hypothesis, such as that every disintegrated molecule of the lowest forms can reproduce the parent-form, and that the molecules are universally distributed, and that they do not lose their vital power until heated to such a temperature that they decompose like dead organic particles.

Alfred Russel Wallace: Letters and Reminiscences, Vol. 1 James Marchant

At present I should prefer any mad hypothesis, such as that every disintegrated molecule of the lowest forms can reproduce the parent-form, and that the molecules are universally distributed, and that they do not lose their vital power until heated to such a temperature that they decompose like dead organic particles.

Alfred Russel Wallace Letters and Reminiscences Marchant, James 1916

Both hybrids and mongrels can be reduced to either pure parent-form, by repeated crosses in successive generations with either parent.

IX. Hybridism. Hybrids and Mongrels Compared, Independently of Their Fertility 1909

For it bears on the view which I have taken of one of the causes of ordinary variability; namely, that the reproductive system from being eminently sensitive to changed conditions of life, fails under these circumstances to perform its proper function of producing offspring closely similar in all respects to the parent-form.

IX. Hybridism. Hybrids and Mongrels Compared, Independently of Their Fertility 1909

In either of these cases, the young or embryo will closely resemble the mature parent-form, as we have seen with the short-faced tumbler.

XIV. Mutual Affinities of Organic Beings: Morphology-Embryology-Rudimentary Organs. Development and Embryology 1909

In two or more groups of animals, however much they may differ from each other in structure and habits in their adult condition, if they pass through closely similar embryonic stages, we may feel assured that they all are descended from one parent-form, and are therefore closely related.

XIV. Mutual Affinities of Organic Beings: Morphology-Embryology-Rudimentary Organs. Development and Embryology 1909

But to return to our comparison of mongrels and hybrids: Gärtner states that mongrels are more liable than hybrids to revert to either parent-form; but this, if it be true, is certainly only a difference in degree.

IX. Hybridism. Hybrids and Mongrels Compared, Independently of Their Fertility 1909

Alternation of Generations—This term is applied to a peculiar mode of reproduction which prevails among many of the lower animals, in which the egg produces a living form quite different from its parent, but from which the parent-form is reproduced by a process of budding, or by the division of the substance of the first product of the egg.

Glossary of the Principal Scientific Terms Used in the Present Volume 1909

These three families, together with the many extinct genera on the several lines of descent diverging from the parent-form (A) will form an order, for all will have inherited something in common from their ancient progenitor.

XI. On the Geological Succession of Organic Beings. On the Affinities of Extinct Species to Each Other, and to Living Forms 1909