Another Pedigree of Webbed Toes 



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A PEDIGREE was recently pub- 

 lished by Schofieldi in the Jour- 

 nal OF Heredity in which a very 

 unusual mode of inheritance was indi- 

 cated. The character involved was a 

 web between the second and third toes. 

 This was transmitted by five web-toed 

 men of three generations to every one 

 of their sons (13 cases) but to none of 

 their daughters (11 cases). Daughters 

 of these webbed toed fathers had 2 

 normal sons and 5 normal daughters. 

 The only parallel case seems to be that 

 found recently by Schmidt^ in the 

 fish Lebestes reticulatus. Schmidt has 

 pointed out that an exclusively male 

 character which is transmitted by 

 father to every son follows exactly 

 the mode of transmission of the Y 

 chromosome. Recent work by Pain- 

 ter^ indicates* that there is an X-Y 

 sex-determining pair of chromosomes 

 in man. 



Another pedigree, involving what 

 seems to be the same trait, webbing of 



the second and third toes, has been 

 sent to the Journal of Heredity by 

 Dr. Ira S. Wile, who calls attention to 

 its failure to follow the rules found in 

 Schofield's pedigree. In three cases 

 there is transmission from father to 

 daughter and in one case there is 

 failure of transmission from father to 

 son. The pedigree indicates that web- 

 bing in this case depends on a single 

 dominant unit with no relation to 

 sex, a conclusion which agrees with 

 that drawn by Hurlin^ from another 

 web-toed pedigree, published earlier in 

 the Journal of Heredity. 



These apparent inconsistencies indi- 

 cate that webbing may be determined 

 by different unit factors in different 

 families. Such a result is not especially 

 surprising. It is known for example 

 that night blindness follows the sex 

 linked mode of inheritance in some 

 families, while acting as a simple 

 dominant in others. 



S. W. 



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> Schofield, Richard, "Inheritance of Webbed Toes," Jour. Heredity, (1922), 12, pp. 400- 



2 Reviewed by W. E. Castle, "A New Type of Inheritance," Sci., N. S., (1921), 53 pp. 339- 

 342. 



' 3 Painter, T. S., "The Y-Chromosone in Mammals," Sci., N. S., (1921), 53, pp. 503-504. 



^ Hurlin, R. G., "A Case of Inherited Syndactyly in Man," JouR. Heredity, (1920), 11, 

 pp. 334-335. 



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