76 GRACE P. HAYS 



in causing the defects which originated during foetal develop- 

 ment. Both the physical deformities and the failure to eat, 

 however, may have been the result of the same physiological 

 disturbance. 



Other than the variations noted the cat seemed to be quite 

 normal. The thymus and pituitary body appeared normal. 

 The thyreoid was a little small when compared to the thyreoid of 

 a normal kitten of the same size. It was at first suspected that 

 the upper leg bones were relatively short but a comparison of 

 the radio-humeral and tibio-femoral indices with those of normal 

 cats of the same age indicated no such unusual condition. The 

 abnormalities under consideration were confined to the feet. 



This case raises several questions. Is the deformity heritable? 

 If so what is the heritable character? What are the relations 

 of the various forms of abnormality^ occurring in the extremities? 

 What are the causes? Are such deformities commonly associated 

 with any other abnormal conditions? 



Poulton ('83, '86), Bateson ('94) and Torrey ('02) have indi- 

 cated that Polydactyly is strongly hereditary in cats. Lewis 

 ('09) and Broman ('04) establish the heritability of both Poly- 

 dactyly and syndactyly among human beings. Broman ('04, 

 p. 62) says, 



Mele, ja vielleicht die meisten angeborenen Missbildungen iind 

 Anomalien sind ausgesprochen erblich, and zwar sowohl Hemmungs- 

 Missbildungen wie andere. Sehr erblich sind z. B. Hypospadie, 

 Poly- und Svndactylie und die angeborene Hiiftgelenksluxation (Hoffa, 

 '04). 



Both these authorities note the frequent association of Poly- 

 dactyly and syndactyly in the same individual. Broman 

 ('04, p. 233) says, 



"Die Syndactyhe ist eine relativ gewohnliche Missbildung, 

 Sie kommt nicht selten entweder mit Perodactylie oder mit 

 Polydactylie kombiniert vor." 



In order to establish a working theory concerning the origin 

 of Polydactyly, where there is a greater than normal number of 

 elements, and of syndactjdy, where the number of elements is 

 less than the normal number, it will be necessary to indicate the 



