PHYSICAL CHARACTERS IN MAN 



8; 



the condition through a mutation, unless possibly his 

 affected parent only had the condition in a slight 

 degree, and so was mistaken for a normal. The 

 actual origin of such a case is naturally difficult to 

 prove, and this can only be done where the conditions 

 in both parents and grandparents are accurately and 

 certainly knowai from observation to be normal. 



Fig. i6. — Radiograph of the Two Hands of a Girl Aged 

 Nineteen, in the Same Family as Fig. 15. (After 

 Drinkwater.) 



That various other modifications of typical brachy- 

 dactyly, in addition to those described above, are 

 inherited in the same way is shown b}^ such records 

 as those recently published by Dr. Drinkwater (191 6), 

 whose accurate work in recording these cases is of 

 great value. He traces through four generations a 

 case of abnormal segmentation of the index and middle 

 fingers, the third finger being much longer than any 



