The elements of genetics / by C.D. Darlington and K. Mather.
- C. D. Darlington
- Date:
- [1949]
Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Credit: The elements of genetics / by C.D. Darlington and K. Mather. Source: Wellcome Collection.
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![INTRODUCTION and nucleus, show that the nucleus must be deciding what kind of hat is grown. The nucleus seems to bear the genotype (Fig. i). Sexual reproduction is just such a transplantation as we see in the alga. A sperm nucleus or generative nucleus of a pollen grain enters an egg cell hundreds or thousands of times larger, and fuses with the female nucleus. Thus the nucleus of the fertilized egg or zygote is of mixed origin; but its cytoplasm is almost exclusively from the mother. The new organism develops from this zygote and shows, S S?xEcf [S] x EJ E Fig. 2. —Larvae of sea urchins: S, Sphaerechinus granulatus\ E, Echinus microtuber- culatus; S J XE the normal cross; [S] X E £, the haploid larva produced by the same cross when the nucleus of the egg has been removed. The larva is then scarcely anything other than a dwarf edition of the sperm parent which is the source of its nuclei (after Boveri 1889). where they differ sufficiently, the characters of father and mother in equal measure. Going a step further, Boveri was able to fertilize a piece of egg, lacking a nucleus, of one species of sea urchin with the sperm of another. The resulting larva (termed a merogon) closely resembled a dwarf of its male parent from which it had derived its nuclei and showed no obvious influence of its female parent from which it had derived its cytoplasm (Fig. 2). We thus see the overriding action of the nucleus. The study of its structure and movements may therefore be expected to tell us why individuals are so constant within themselves in their inborn character and also why they differ from one another.](https://iiif.wellcomecollection.org/image/b1802094x_0025.JP2/full/800%2C/0/default.jpg)
