A CASE OF A SYNDACTYLOUS CAT 79 



greater degree than ordinarily, superfluous elements might be 

 formed and a condition of Polydactyly result. If the syndactyly 

 or Polydactyly occurred slightly later, after the anlagen of the 

 digits were differentiated, it would have to result either from 

 a fusion or from added separation. Syndactyly might be a 

 result of some early fusion of distinct or partially distinct ele- 

 ments and Polydactyly a result of a division of one or more of 

 the digit anlagen. Broman ('04) supports both the idea that 

 syndactyly arises early and the idea that it may be in some way 

 a pressure effect. He says (p. 651). 



In anderen Fallen ist die anscheinend kleinere Zahl der Finger 

 (Zehen) auf mangelhafte Trennung (Sjiidactylie), der in normaler 

 Zahl vorhanden Fingeranlagen zuriickzufiihren (fig. 199-202 s. 232). 

 Die Skeletteile zweier mangelhaft getrennten Finger konnen entweder 

 getrennt bleiben oder verschmelzen (Syndactylie ossea). 



He does not explain what causes this defective separation nor 

 does he give any evidence for assuming th-at syndactyly is brought 

 about at this time. In regard to pressure he says ('04, p. 233), 



"In vielen Fallen von Syndactyhe scheint man berechtigt zu 

 sein, die Missbildung auf friihzeitige Druckwirkung und Raum- 

 beengung durch das Amnion zuriickzufiihren (Klaussner 1904)." 



Neither of these views, which are as yet unsupported by ade- 

 quate evidence, involves a consideration of the relation of syn- 

 dactyly to Polydactyly. There is no definite evidence pointing 

 to distinct origins of these two conditions. On the contrary 

 they are frequently found in close relation. This suggests that 

 both may be due to the operation of a single fundamental factor. 



It would be interesting to determine whether or not the 

 heritable character of each of these abnormalities might be a 

 tendency to instability in the formation of the extremity. If 

 such were the case, the resulting Polydactyly or syndactyly 

 would depend upon individual conditions; if it were not, the 

 two might be fundamentally different in origin. In the recorded 

 strains of polydactylous cats there was no constant number of 

 digits characteristic of a given family, but there seemed to be 

 a tendency to increase the number of superfluous digits in the 



