328 A Second Braclii/dacti/lons Famihi 



Farabee's neighbourhood, he would bo liktdy to get a more complete 

 record than I could obtain, and hence the difference in the second 

 generation in the two charts is accounted for. 



It will be observed that Farabee has here indicated the descendants 

 of abnormals only ; my chart includes the offspring of norinals us well 

 as ahnormals. 



The rest of this paper i-efers exclusively to the English family which 

 I have recently studied. 



The abnormality, wherever it exists at all, affects hotli hands and 

 both feet, as well as the stature. Both hands and both feet are always 

 affected symmetrically. 



The chart includes 50 abnormal individuals, of whom .S4 are living. 

 Through the great kindness of these people I have been able to obtain 

 photographs of the right hand of 30 of them, and radiographs of the 

 hand and foot of 29, as well as a few full length portraits ; — a most 

 satisfactory record, when one considers their very natural reluctance to 

 do anything calculated to draw attention to them individually. In fact 

 there are only two adults whom I have failed to persuade to pay a visit 

 to the photographer and radiographer. 



An Example of Mendelian Inhekitance. 



Students of Mendelism will at once recognise that Brachydactyly as 

 illustrated by this family conforms in a remarkable degree with certain 

 laws enunciated by Uregor Mendel. One of these laws states that a 

 ' dominant" character is transmitted only by a member showing that 

 character, and not by a member showing the " recessive " character, 

 and that the recessives always breed true to the recessive character. 



In this family the normal individuals are "recessives," and according 

 to the theory cannot bear abnormal (short-fingered) children; and the 

 chart shows that the normals have had normal children only. In other 

 words, every abnormal child has an abnormal parent. As there has 

 been no inter-uiarrying oi abnormals, it follows that each abnormal 

 child has had one abnormal and one normal parent — one showing 

 Brachydactyly, and one with the normal type of hand and foot. 



When abnormal individuals — the offspring of parents of two distinct 

 types — marry normals, the offspring (in conformity with Mendel's Law) 

 should be of both types, in appi'o.ximately equal numbers — 50 per cent, 

 of normals and 50 per cent, of abnormals. That is what Mendel found 



