. Botany of the living plant. Botany; Plants. HKRKDITV AND VARIATION (z) Each chromosome separates into exactly equal halves (chromatids) which arc distributed to opposite poles t the dividing cell. Hence, (3) each daughter nucleus receives eld exactly equal share "f tin- chromosome material of the parent QU< leus (Fig. 420). Proph ase B Y AtetepAase 1 (division cft/ip nuc/eus \ Anaph ase V Te/op/iase (ftro nuc/ei). a, atfacnmenf c<7/7sfr/cf/0/z. Fie. 429. Diagram showing the changes undergone by two chron. 111 the course of mitosis. (From Crane and Lawrence alter Darlington.) If, a
. Botany of the living plant. Botany; Plants. HKRKDITV AND VARIATION (z) Each chromosome separates into exactly equal halves (chromatids) which arc distributed to opposite poles t the dividing cell. Hence, (3) each daughter nucleus receives eld exactly equal share "f tin- chromosome material of the parent QU< leus (Fig. 420). Proph ase B Y AtetepAase 1 (division cft/ip nuc/eus \ Anaph ase V Te/op/iase (ftro nuc/ei). a, atfacnmenf c<7/7sfr/cf/0/z. Fie. 429. Diagram showing the changes undergone by two chron. 111 the course of mitosis. (From Crane and Lawrence alter Darlington.) If, as is generally assumed, the heritable qualities of the organism are local- ised in the chromosomes—as so-called genes—mitosis dearly provides a mechanism by means of which these qualities are transmitted unchanged each somatic division. The fact that new individuals produced by veg« tative propagation (Chapter XIII) exactly resemble the parent plant bears out this conclusion. Meiosis. The formation of tetraspores (such as pollen-grains, spon a t Pteridoph and Bryophytes, tetraspores of Rhodophyceae, ascospores and basidiospon involves two divisions of the nucleus accompanied by one division of the chromosomes; as a result, the chromosome number is halved. Mine four tetraspores are produced from each spore mother cell, the whole proa is often described as a 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 Bower, F. O. (Frederick Orpen), 1855-1948; Wardlaw, C. W. (Claude Wilson), 1901-. London, Macmillan and Co. , ltd.
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