Identifier: hygienedentalge00turn (find matches)
Title: Hygiene, dental and general
Year: 1920 (1920s)
Authors: Turner, C. E. (Clair Elsmere), 1890-1974 Rice, William
Subjects: Hygiene Teeth
Publisher: St. Louis, C. V. Mosby
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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ited from the male parent. Itwould therefore be present in all of the body cells of the hy-brid but when this pair of chromosomes again become sep-arated in the production of sex cells they would producecells of different types. Therefore, we may have from thisgeneration of hybrids, ova containing a factor for pigmen-tation and ova lacking the factor for pigmentation. Like-wise, we may have spermatozoa with this factor and otherswithout it. so that there are four possibilities in the matingof cells within the uterus which must be in reality a matterof chance. The female cell with the character for blacknessmay unite with the male cell also having that characteristicand in that case the offspring produced receives the same in-heritance from both parents so far as this characteristic is HYGIENE OF REPRODUCTION 83 concerned, and therefore it is a pure black which willalways produce black offspring. There is an exactly oppositepossibility, namely, a union of two cells neither of which has
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Fig. 16.—Diagram illustrating the mechanism by which the unit factor, color,is inherited in guinea pigs. Animal A is a black female of pure stock. Such ananimal is called homozygous and all of its sex cells are alike in carrying theunit character in question. Animal B is a homozygous white male; none of the sexcells have the characteristic for blackness. Animals C (female) and D (male)are hybrids. In each case half of the sex cells carry the characteristic forblackness and half of them lack this characteristic. When C and D are crossedthe offspring of the second generation are in the ratio to three black to onewhite. The diagram illustrates each possible chance-combination of sperm andegg and it will be seen that, of the second generation animals, E is homozygous,F and G are heterozygous like C and D, and H is a homozygous white. the characteristic for blackness. Such a union results in awhite pig of pure stock so far as color is concerned. Two other possibilities involve the mating

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