Understanding heredity : an introduction to genetics / Richard B. Goldschmidt.

  • Goldschmidt, Richard, 1878-1958.
Date:
[1952]
Catalogue details

Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Understanding heredity : an introduction to genetics / Richard B. Goldschmidt. Source: Wellcome Collection.

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    to the important conclusion that individuals known to be geneti¬ cally, hereditarily, different may, despite this difference, look exactly alike. In other words, the visible, external type does not necessarily give us any information about the hereditary constitution of an individual. Our original question remains: How can we determine what is inherited? 6 7 8 9 10 11 12 13 14 Millimeters 17 18 19 11 12 13 14 15 16 Millimeters 11 12 13 14 15 16 17 18 Millimeters 20 21 Millimeters Fig. 3. A selection experiment with beans taken from those drawn in Fig. 2. a, b, c, d, the selected beans; and below, their ofiFspring. a and Ъ, alike in size, belong to different hereditary strains ( small and medium ) ; so do с and d, respectively (medium and large). Illustration of the meaning of pheno- type and genotype. Let us make a test. We plant some of the 13-mm. beans that the farmer gave us without telling us from which plot or plots they came. The following year one plant from one such seed produces beans with a size variation from 6 to 14 mm. and an average length of 10 mm. Only now is it clear that that particular parental bean came from the hereditarily small strain. To its off¬ spring it has transmitted the genetic average size, not its variant 10