Heredity and eugenics ; a course of lectures summarizing recent advances in knowledge in variation, heredity, and evolution and its relation to plant, animal and human improvement and welfare / by William Ernest Castle, John Merle Coulter, Charles Benedict Davenport, Edward Murray East, William Lawrence Tower.

Date:
[1912]
Catalogue details

Licence: Public Domain Mark

Credit: Heredity and eugenics ; a course of lectures summarizing recent advances in knowledge in variation, heredity, and evolution and its relation to plant, animal and human improvement and welfare / by William Ernest Castle, John Merle Coulter, Charles Benedict Davenport, Edward Murray East, William Lawrence Tower. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    Many peculiarities of the skeleton are clearly due to a positive determiner that inhibits the normal development. Thus the case is cited of a father with a deformed clavicle or collar bone; of his seven children, five have the clavicles of a more or less abnormal form. Likewise in polydactyl- ism, or extra-fingeredness, there is some positive factor that induces the formation of the extra toe; but normal- toed persons of a polydactyl strain, being without the determiner, will have all children with five toes only. The same is true of brachydactyly. There is something that stops the growing of the fingers to the normal length, 0 (§ S H ^ [^ \^% ®^ (u) (d) [^[n] [d] (n)^ 3N ^ [n] [d][b] (n)(d)^[^[d] ION 4N [^® 6N ^[d]^ ^ 4N 5N 3N ® ^©^[d] (n) 2N 2D ® Fig. 85.—Pedigree of a family with diabetes insipidus. D, aiiected persons SO that if the determiner gets into the zygote from either side of the house, the child will be short-fingered, but not otherwise. Diabetes is a common disease which seems to belong to this category (Fig. 85). Here again two normal parents may have defective children but only when the defect occurs in the germ plasm of both sides of the house. The applications of these facts regarding abnormalities and diseases that are of a positive sort have an importance for eugenics. They are all characterized by this, that they usually appear in each generation and do not skip genera-