CHAP. XIII.] 



UNION OF DIGITS : MAN. 



357 



Before going further certain points are to be noted. First, the 

 union as shewn in the figures is a union or compounding as of optical 



I 



n 



Fig. 104. Cases of syndactylism. I, II and III. A progressive series illus- 

 trating degrees in the union of rnedius and annularis in the hand. IV. Case of 

 union of index and medius of the foot. The union is incomplete peripherally. 



(After Annandale.) 



images in Bilateral Series, and is not like that of parts in Successive 

 Series. Next, the union of the bones is more complete peripherally and 

 less complete centrally. The latter is a rule very commonly observed in 

 cases of the union of the bones of digits both in Man and other mam- 

 mals. This statement is made without prejudice to the other fact that 

 in the least state of syndactylism as manifested by union of the soft 

 parts, it is the most central phalanges which are united. Such a case 

 of partial union between II and III in the foot 1 is shewn in Fig. 104, IV 

 (Annandale, I. c, fig. 34). The rule that in the lowest condition of 

 syndactylism of the bones it is commonly at the periphery that the 

 union is most complete is also difficult to understand in connexion with 



1 Compare several remarkable cases of this variation in one family, le Clerc, 

 Mem. soc. Linn. Normandie, ix. p. xxvi. 



