62 Hereditarif S//iidac(!/lLsin <md Poh/dactjilism 



there is also partial webbing between the 3rd and 4th toes. This goes 

 to show that the more complete the bony abnormality the greater the 

 tendency to webbing. It would be a fair assumption in this family at 

 any rate to state that the syndactyly present is not a character 

 separate from the bony abnormality but only a feebler expression of it. 



While the four descendants of II. 7 who have been examined show 

 that both sides of the body are e(itially affected, the five descendants of 

 II. 2 .show that the right side is affected twice as often as the left side 

 in the proportion of 8 limbs to 4 limbs. The variability in hereditary 

 deformities of the hands and feet has been noted by other writers. 

 Fotherby(l) in his account of a claw hand and claw foot family states that 

 a female of the 4th generation had 7 fingers on one hand and G on the 

 other. Anderson (2) in describing a similar claw hand family points out 

 that " the morbid features were not confined to a suppression of parts. 

 Syndactyly, compensatory hypertrophy, distortion of the articulations 

 and multiplication of parts were also present." J. S. Muir{3) and 

 C. Lucas(4) also describe great variability in hereditary digital defor- 

 mities. 



In the family here described, while there is undoubtedly some degree 

 of variability in the deformity, yet the skiagraphs show clearly that it 

 is the 4th digit of both hands and feet that is consistently affected 

 either by complete or partial reduplication. In the future, X-ray photo- 

 graphs of the hands and feet of affected families will no doubt show 

 that there is a greater uniformity in the nature of these hereditary 

 deformities than has hitherto been supposed. 



Dwight(5) has shown that there is considerable variation in the bones 

 of what are regarded as normal hands and feet. He explains that this 

 is due to the persistence of embryonic centres indicating bone which 

 normally disappear or fnse with others. That being so, it is to be 

 expected that an hereditary abnormality such as is present in this 

 family, and which must necessarily appear at the very earliest period 

 of embryonic development, would also undergo certain variations due 

 to absorption and fusion. 



It is interesting to observe that in the majority of the affected 

 hands in this family sesamoid bones are present at the second, third 

 and fourth metacarpo-phalangeal joints where they are not usually 

 present in normal hands. As these bones are frequently present 

 in embryonic hands it can be inferred that in these affected hands 

 the processes of absorption are below normal. At an early stage 

 of embryonic development the affected parts in the members of this 



