Heredity : in the light of recent research / by L. Doncaster.
- Doncaster, L. (Leonard), 1877-1920.
- Date:
- 1910
Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Credit: Heredity : in the light of recent research / by L. Doncaster. Source: Wellcome Collection.
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![AP. Il] HEREDITY 127 Boveri [3] to believe that the subsequent develop¬ ment of the cells of the embryo depends on the distribution of the chromosomes in the abnormal divisions consequent on double fertilisation. And Herbst [16] has obtained sea-urchin larvae made by crossing distinct species, which on one side of the body resemble one parent, and on the other side the other parent. He shows that these diiferences are connected with diiferences in the size of the nuclei of the two sides, and that probably the part with maternal characters contains only maternal nuclear substance, while the part showing the paternal character has nuclei derived from both parents. But probably the best evidence for regarding the chromosomes as bearing the essential determinants for hereditary characters is provided by the behaviour of the chromosomes themselves in the maturation divisions of the germ-cells. It has been pointed out that at these nuclear divisions the chromosome number is halved, and restored to the full number again in the next generation by the union of two germ-cells each bearing the half-number. Now it has been found in certain cases that the chromosomes are not all alike, but diíFer among themselves in size and shape, and when this is so it can be seen that the nucleus just before maturation contains two of each kind. If the different kinds of chromosomes](https://iiif.wellcomecollection.org/image/b18030117_0144.JP2/full/800%2C/0/default.jpg)
