172 MENDELISM CHAP. 



whole of the body is much stunted, and the fingers and 

 toes appear to have two joints only instead of three (cf. 

 Figs. 32 and 33). The inheritance of this peculiarity has 

 been carefully investigated by Dr. Drinkwater, who col- 

 lected all the data he was able to find among the members 

 of a large family in which it occurred. The result is the 



FIG. 33. 



Radiograph of a brachydactylous hand. ->. 



pedigree shown on p. 173. It is assumed that all who 

 are recorded as having offspring were married to normals. 

 Examination of the pedigree brings out the facts (i) that 

 all affected individuals have an affected parent ; (2) that 

 none of the unaffected individuals, though sprung from 

 the affected, ever have descendants who are affected, and 

 (3) that in families where both affected and unaffected 



