Page:Popular Science Monthly Volume 84.djvu/11

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THE MECHANISM OF HEREDITY
7

Fig. 2. Diagram to illustrate inheritance of two pairs of Mendelian characters, viz., yellow-green and round-wrinkled peas. The 16 small squares represent the composition of the 16 F2 peas; viz., 9 YR, 3 YW, 3 GR, 1 GW.

In each animal or plant there are in general two of each kind of chromosomes.[1] One of each kind has come from the father, one from the mother, at the time of fertilization (Fig. 3, a). A hybrid likewise

  1. Except in those eases where the male has one less chromosome than the female. In such cases the single sex chromosome of the male has no mate.