FURTHER DATA ON WEBBED TOES 



W. E. Castle 

 Harvard University 



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WEBBED TOES IN FEMALE LINE ONLY 



Figure 9. Considerable data have been presented previously in the Journal of Heredity 

 on the inheritance of this character. In one case webbed toes appeared only in the male line, 

 in all the rest of the families, both sexes were affected. In this family only the women have 

 webbed toes, suggesting that the character is carried in the Y-chromosome. 



THE INHERITANCE of webbed 

 toes has been discussed in the 

 Journal of Heredity by Hurlin/* 

 Schofield," Schultz,'' and Wright' and 

 six different pedigrees bearing on the 

 matter have been presented. A seventh 

 pedigree has been sent in by a corre- 

 spondent who points out that it does 

 not accord with the interpretation of 

 Y-chromosome inheritance suggested by 

 Schofield's data." In this, a Delaware 

 family, the character has been observed 

 in females only and is traced through 

 three generations, involving four in- 

 dividuals (See Figure 9). It is note- 

 worthy that there were three unaffected 

 sisters as well as four iniaffected 

 brothers of the affected individual in 

 generation II. The idea that the Y- 

 chromosome may be the vehicle of 

 transmission of the character suggested 

 in connection with the Schofield pedi- 

 gree is clearly not applicable to this 

 family, but this case could be brought 

 into harmony with that interpretation 

 if we suppose that in man, as in certain 



fishes^' ^' ^ either the X or the Y chro- 

 mosome may be the vehicle of trans- 

 mission, and genes may cross over from 

 X to Y or vice versa. In this family 

 obviously the X-chromosome would be 

 a suitable vehicle, whereas in the Scho- 

 field family, the Y-chromosome alone 

 would meet the requirements. 



But if we extend the inquiry to other 

 pedigrees reported by Huiiin. Schultz, 

 and Wright, difficulties are encountered. 

 Considering together all the seven ped- 

 igrees, sixty-five cases of transmission 

 from parent to child are reported. The 

 transmission is from father to son in 

 forty-one cases, from father to daugh- 

 ter in seventeen cases, from mother to 

 son in three cases, and from mother 

 to daughter in four cases. Aside from 

 the fact that the character is more 

 often reported in males than in females, 

 there is no reason to think that the 

 character is either sex-linked or sex- 

 limited. It is a simpler hypothesis to 

 suppose that the character depends 

 on the transmission of a dominant gene 



*For Numbered References, see "Literature Cited" at end of article. 



209 



