The cell in development and inheritance . ed in the reduced number(twelve in the Uly, eight in the onion) at the first division of thepollen-mother-cell, and in the female at the first division of themother-cell of the embryo-sac. The subsequent phenomena differin a very interesting way from those in animals, owing to the factthat the two maturation-divisions are followed in the female by oneand in the male by two or more additional divisions, in both of whichthe reduced number of chromosomes persists. In the male the twomaturation-divisions give rise to four pollen-grains, in the female to 1
The cell in development and inheritance . ed in the reduced number(twelve in the Uly, eight in the onion) at the first division of thepollen-mother-cell, and in the female at the first division of themother-cell of the embryo-sac. The subsequent phenomena differin a very interesting way from those in animals, owing to the factthat the two maturation-divisions are followed in the female by oneand in the male by two or more additional divisions, in both of whichthe reduced number of chromosomes persists. In the male the twomaturation-divisions give rise to four pollen-grains, in the female to 1 Cf. p. 269. 264 REDUCTION OF THE CHROMOSOMES the four primary cells of the embryo-sac (Fig. 132); and these twodivisions undoubtedly correspond to the two maturation-divisions inanimals. In the female, as in the animals, only one of the fourresulting cells gives rise to the ^gg, the other three corresponding tothe polar bodies in the animal , though they here continue todivide, and thus form a rudimentary prothallium.^ The first-men-. :(r ^ B
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectcells, bookyear1902
