486 THOMAS DWIGHT UN THE FUSION OF HANDS. 



lation, probaljly a .splitting, which is followed by an attempt at duplication, is at first sight 

 a very attractive one. Certain experiments on lizards' tails give it support from analogy. 

 It accounts for cases in which the lesion was .so slight that Init a part of one finger is 

 involved, or so deep as to affect a whole extremity. There are, however, certain very serious 

 difficulties. What, it may be asked, becomes of the parts that should form the radial 

 side of the hand in a case like the present one ? Another difficulty is that in a large pro- 

 portion of the cases both hands and both feet are affected. Zander' argues that there is 

 no impossibility in the occurrence of symmetrical lesions l)y the amnion. In support of his 

 Adews it may be stated that very often, perhaps usually, these malformations of both 

 sides are not absolutely .symmetrical, and therefore the more likely to have such an injury 

 for their proxinuite cause. If these objections can be met this seems the most promising 

 theory. Taruffi. while admitting our ignorance, speaks of "exaggerated gemmation." which 

 conveys no explanation. All are now agreed that there is nothing to be said in favor of a 

 double germ. It is remaikable that this view should have survived so long. A century 

 and a half ago M. de Mairan' wrote on this subject: ''11 faut devorer bien des prodiges, 

 lorsque on dit du bout des levres que 1« foiination des monstres pent etre expliquee par 

 la confusion des germes." 



DESCRIPTIOX 'IF I'LATES. 



The foUowiug letters have always the same signitioaucc. E, the fused external condyles ; I, the normal iuterual 

 condyle; 1^, the extra Internal condyle; 0,the normal olecranon: O^, the extra olecranon. 



PL.iTE 43. 



J. Cast of forearm and hand, showing the back of the elbow and the palm of tlie hand. 



2. The same cast, showing the back of the hand. 



3. The scapula and upper part of humerus. 

 i. Back and outer side of elbow. 



5. Front of elbow. 



PLATE 44. 



1. Front of the upper end of the ulnae. R indicates an articular sui-face on the front of the extra ulna simulating 

 a part of a radius. 



2. Lower end of the humerus seen from below. The anterior surface is al)ove. 



3. Lower end of the humerus seen from the outer side. 



4. A model, showing the n.ature of the malformation. The piece of the extra humerus should, perhaps, have been 

 put on so as to form more nearly a right angle with the left humerus. 



.5. The front of Uic wrist and hand. U A, ulnar artery; U Aj, extra ulnar artery ; U K, uln.ar nerve; I' Nj. extra 

 ulnar nerve. M, M, branches of median nerve. 



Virchow's Archiv, Bd. 12.-., s. 47'.» and 480. 1891. •' Hist. Acad., 1742. 



