508 



HtnVIAN INHERITANCE 



their length (Fig. 145). It is due to the fact that the fin- 

 gers have only two joints in place of the usual three. A 

 brachydactylous individual ordinarily transmits the pe- 

 culiarity to about one-half of his children, when mated to 

 a normal woman. His affected children transmit it in the 



Fio. 145. — Brachydactylous Hands. 1, shows the proportionally 

 short broad hands and 2, an X-ray photxigraph of a normal and 

 brachydactylous hand. Note that in the latter the last two bones 

 of each finger are fused together to form a single short one. 



Plate, Vererbungslehre. Englcmann. 



same way but the normal children probably never trans- 

 mit it to their descendants. From these data one may 

 conclude that a single factor difference is responsible and 

 that the gene for brachydactyly is dominant over the 

 corresponding normal gene. In the cases of which there 



