The Inheritance of ''Thumb-fingerness' 

 in a Short-fingered family. 



4 Case of ^endelian Inheritance in IVIan. 



An Address delivered to the Mendel Society 

 on June 6th, 1910. 



By H. DRINK\A/'ATER, M.D., M.R.C.S., F.R.S. Edin. 



The family which will be described in this paper 

 presents a rare and easily-recognised deformity which 

 has affected at least seven generations. It is interest- 

 ing in many ways. Its hereditary character is 

 particularly striking, for it is practically identical 

 in every affected individual, and the student of 

 Mendelism will be impressed by the close conformity 

 of the numbers affected to theoretical expectations. 



I shall avoid all technical terms as far as possible, 

 so that the essential features may be understood by 

 the readers who are unfamiliar with anatomy. 



The genealogical chart (Plate 1) shows all the 

 individuals, as far as they can now be traced, through 

 the last seven generations. Whether the abnormality 

 began with the woman at the head of this chart, or 

 whether she inherited it from one of her parents, is not 

 now known. There is every reason to believe that its 

 first appearance was as we now see it, and that it 

 did not appear or develop by a gradual process. In 



