. Advanced biology. Biology; Physiology; Reproduction. notcVu vestigial miniature wing clvcb vvxng^. ruStimentory truncode normal boci* eve eyeless eye T. H. Morgan and his associates have observed the appearance of hundreds of new characters, mutations, in fruit flies. change, a mutant is produced, but that germinal variations may also arise in other ways. Morgan has shown that mutations sometimes arise as a result of one gene or more actually changing in character. He has identified over 400 characters which are carried by the eight chromosomes of the fruit fly (four chromosomes in each germ
. Advanced biology. Biology; Physiology; Reproduction. notcVu vestigial miniature wing clvcb vvxng^. ruStimentory truncode normal boci* eve eyeless eye T. H. Morgan and his associates have observed the appearance of hundreds of new characters, mutations, in fruit flies. change, a mutant is produced, but that germinal variations may also arise in other ways. Morgan has shown that mutations sometimes arise as a result of one gene or more actually changing in character. He has identified over 400 characters which are carried by the eight chromosomes of the fruit fly (four chromosomes in each germ cell). He believes that each character is determined by a gene in a chromosome. Therefore, there are many genes in each chromosome. Experimental work in heredity makes it seem highly probable that these tiny units of inheritance are present in the chromosome, and if they change in character it again seems plausible that a germinal variation would result. (c) Crossing-over of genes. Several scientists have done experi- mental work that would seem to show that sometimes the genes actually cross over from one chromosome to another. Just be- fore reduction-division, the chromosomes always arrange them- selves side by side in pairs. In the fruit fly there would be four. 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 Wheat, Frank Merrill; Fitzpatrick, Elizabeth T. New York ; Boston [etc. ] : American Book Company
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Keywords: ., bookcentury1900, bookdecade1920, booksubje, booksubjectphysiology
