478 



OEIGIN AND DISTRIBUTION OF MAN. 



[Cii. XLIII 



The frequent re-growtli of supernnmerary digits after they 

 have been cut off is another extraordinary fact which m ust 

 not be lost sight of by those who are disposed to speculate on 

 the nature and cause of this phenomenon. In one instance 

 that of a person now living, the additional finger^ when the 

 infant was about six weeks old^ was removed at the joint, and 

 as soon as the wound healed, the digit began to grow, on 

 which the operation in about three months was repeated 

 when the finger was once more reproduced including a bone. 

 In another example cited by Dr. Carpenter of a thumb double 

 from the first joint, the lesser thumb being furnished with a 



rem 



^ 



Mr. Darwin regards these supernumerary digits in man as 

 retaining to a certain extent an embryonic condition and 

 resembling in this respect the normal digits and limbs of the 

 lower vertebrate classes which are so prone to reproduction. 

 Spallanzani cut off the tail and legs of the same salamander 

 six times successively, and Bonnet cut them off eight times, 

 and they were always renewed. The pectoral and tail-fins 



many 



times in their pectoral fins 



more 



time. Fishes have some- 

 than five, sometimes as 



metacarpal and phalangeal bones forming 



so many rays, and occasionally bearing bony filaments, which 



together clearlj 



represent our digits with their nails. 



So 



again in certain extinct reptiles, the Ichthyopterygia, ^ the 

 digits may be scA^en, eight, or nine in number, a significant 



m 



Ml 



win therefore suggests that the excess in number and the 

 power of re-growth of the supernumerary digits in man may 

 be an instance of reversion to an enormously remote and 



multidi 



of very inferior 



t 



As the 



number five is so strictly adhered to in the digits of all the 

 higher vertebrata, and is at least never exceeded as a rule in 

 any living reptile, bird, or mammal, the excess above alluded 

 to is generally regarded as a monstrosity, the more so because, 



common 



* Darwiiij Origin of Species, chap. xii. 

 t Ibid. 



I See above, p. 291, on Darwin's 



theory of Pangenesis, 



/ 



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i 



I 



