. Biology. Biology. 222 THE PERPETUATION OF ADAPTATIONS of the hybrid germ cells, whereby the yellow and green factors are separated from one another, so as to produce germ cells having only one factor for green or for yellow. This is known as Mendel's principle of segregation. The hybrid ovule containing both factors is said to be heterozygous, and the two factors for the same character (here color) are called allelomorphs, one of which is dominant, the other recessive. If only one type of factors is present in an ovule, it is said to be FIG. 95.—Example of Mendelian inheritance
. Biology. Biology. 222 THE PERPETUATION OF ADAPTATIONS of the hybrid germ cells, whereby the yellow and green factors are separated from one another, so as to produce germ cells having only one factor for green or for yellow. This is known as Mendel's principle of segregation. The hybrid ovule containing both factors is said to be heterozygous, and the two factors for the same character (here color) are called allelomorphs, one of which is dominant, the other recessive. If only one type of factors is present in an ovule, it is said to be FIG. 95.—Example of Mendelian inheritance in which the hybrid (Fi) is intermediate between the two parents, but showing segregation of the two factors in the germ cells giving in the Ft generation the proportion of i : 2 : i. The cross is made between white and red races of Mirabilis jalapa (the "four o'clock"). The hybrid (F\) is pink, and these when inbred give white, pink, and red flowers in the proportion of i : 2 : i (F»). (From Morgan.) Now if the hybrid plants are self-fertilized, , through union of their own germ cells, and if segregation of factors occurs dur- ing the formation of these germ cells in both anthers and ovules, then the following combinations may occur (Fig. 94). The green-bearing anther may unite with a green-bearing ovule, and the result is green (homozygous); or a green-bearing anther. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Calkins, Gary N. (Gary Nathan), b. 1869. New York, H. Holt and company
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