90 HEREDITY AND EUGENICS 



to North America. The malformation consists in 

 a shortening of the second phalanx of the second 

 fingers and toes only, and is called brachyphalangy. 

 There is no shortening of the stature. The condition 

 occurs in two degrees: (i) so slight as to be often 

 overlooked or even invisible; (2) more extreme, 

 probabh^ due to the presence of a modifying or 

 intensifying factor. The inheritance is that of a 

 simple Mendelian dominant. It has been traced 

 through five generations of descendants from a 

 brachyphalangous woman born in Norway in 1 764. 

 Detailed knowledge of the earlier generations is 

 obtained from a carefully kept " family book." In 

 two lines descended from an affected daughter and 

 an affected son of this woman, every individual is 

 recorded. In one case intermarriage within affected 

 lines apparently produced an individual homoz3^gous 

 for the character. She was a cripple without fingers 

 or toes, and died at the age of one year, being unable 

 to develop. This shows how serious even a slight 

 abnormality ma}^ become if present in the homoz3^gous 

 condition. It corresponds with many of the lethal 

 factors known in Drosophila. The writers refer to 

 Mackinder's (1857) record of a family, in which 

 brachyphalangy combined with h3^pophalangy (less 

 than five fingers) was transmitted for six generations 

 in the manner typical for a Mendelian dominant 

 character. This was in 1857, before even Mendel's 

 original work was done. 



Cragg and Drinkwater (191 6) describe a much more 

 extreme case, w^hich Mohr and Wriedt refer to 

 as h\"pophalang3^ combined with brachyphalangy. 

 There is an entire absence of the distal phalanges 

 from all digits except the thumb and big toe, and an 

 extremely abortive condition of the middle phalanx 

 in the same digits. Nails are absent. The con- 

 dition was traced as a Mendelian dominant through 



