. Domesticated animals and plants; a brief treatise upon the origin and development of domesticated races, with special reference to the methods of improvement. Breeding; Domestic animals; Plants, Cultivated. HOW c:iIy\RACTERS ARE TRANSMITTED 125 bearing both silk and tassel and producing both ovules and pol- len grains, each new kernel being independent of its neighbors. Fertilization in general. This, roughly speaking, is characteristic of fertilization in general, whether plant or animal. A small male cell (the pollen grain in plants or the spermatozoon in animals; meets and fuses with the
. Domesticated animals and plants; a brief treatise upon the origin and development of domesticated races, with special reference to the methods of improvement. Breeding; Domestic animals; Plants, Cultivated. HOW c:iIy\RACTERS ARE TRANSMITTED 125 bearing both silk and tassel and producing both ovules and pol- len grains, each new kernel being independent of its neighbors. Fertilization in general. This, roughly speaking, is characteristic of fertilization in general, whether plant or animal. A small male cell (the pollen grain in plants or the spermatozoon in animals; meets and fuses with the larger 1 female cell (ovule in plants or ovum in animals), which is thereafter capable of developing into a new in- dividual possessed of all the characters of both parents. The method of effecting this union of the nuclei in fertilization and the time at which it takes place vary greatly in different species. In many plants both sex cells are borne by the same indi- vidual, either in one flower, as in the apple and the elm, or in separate flowers, as in corn.^ In others, as the chestnut and the box elder, the male flowers are borne on one plant and the 1 Though the female cell is always larger than the male, the nucleus, which seems to be the essential part, has the same number of chromosomes (see chromosomes), so that the male and the female parents have identical powers in transmission. The differences in size are apparently due to the amount of protoplasm surrounding the nucleus, probably as food material for the develop- ing young and in no way connected with heredity. This difference is some- times great, as in the egg of the hen, most of which is food material for the developing chick, while the male cell is microscopic. 2 This bisexuality, or hermaphroditism, is also found in certain lower animals, as the Fig. 19. Kernels of corn growing on the tip of the tassel; occasional but not common. Please note that these images are extracted from scanned page images
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Keywords: ., bookauthordavenpor, bookcentury1900, bookdecade1910, bookyear1910
