414 



The Journal of Heredity 



the hands are similar the feet are 

 likely to be unlike, and vice versa, so 

 that complete correspondence between 

 the two sides of an individual, and ex- 

 tending to both hands and feet, is ex- 

 tremely rare in single individuals, or 

 may be said never to occur, while in 

 duplicate twins the phenomenon is uni- 

 versal and occurs in both members. 



As an excellent illustration of the 

 palm and sole prints of duplicate twins 

 we may first present a complete set 

 from the two M boys of Port- 

 land, Me., taken about fourteen to fif- 

 teen years ago when they were twelve 

 years old. Aside from being perfect 

 duplicates these prints show in the 

 hands the full set of eleven possible 

 patterns to be expected in a palm when 

 in its most complete form, as follows : 



S apical patterns ("finger-prints"). 

 4 interdigital patterns (below the four in- 

 tervals). 



1 thenar (at the base of the thumb). 



1 hypothenar (upon the fleshy pad on the 

 side of the palm corresponding to the 

 little finger). 



11 



As is universal in man, in cases where 

 these patterns occur at all, the first inter- 

 val between thumb and index, is found 

 in close association with the true thenar, 

 placed just below it, together making 

 a sort of double pattern at the base of 

 the thumb. As is also usual in such 

 cases the interdigital member of this 

 compound pattern is small or vestigeal 

 and is represented by a simple loop, 

 opening upwards or distally between 

 digits 1 and 2. On the two left hands, 

 as would be expected from the fifth rule 

 above, the record is nearly as complete 

 as to the presence of the eleven pat- 

 terns, save that in both the second in- 

 terdigital, between digits 2 and 3, is 

 wanting, although its place is defined 

 clearly by a marked-off area where it 

 would be expected. This pattern is 

 normally of rare occurrence, and even 

 when present is scarcely ever more 

 than a small loop, involving few ridges. 

 A whorl here has not as yet been 

 reported. 



The occurrence of all the typical 



eleven palmar patterns, such as is seert 

 in all four of the hands of this set, 

 is in single individuals one of the 

 rarest phenomena. Among more than 

 1,200 single individuals my coUectioa 

 shows it but once or twice. The com- 

 bination of the true thenar with the 

 first interdigital is almost constant when 

 either pattern appears at all, but in 

 the white race this is only in about 

 4% of all cases, so that in any two- 

 individuals taken at random, if one of 

 them has this pattern, the other has 

 just one chance in twenty-five of hav- 

 ing it also. One must acknowledge,, 

 however, that in children of the same 

 family, where one parent has such a 

 pattern, it is almost certain to appear 

 in all or nearly all. Similarly, the per- 

 centage of occurrence of each of the 

 other patterns must be reckoned with 

 by itself, and the total chance of the 

 appearance of each and every one of 

 the typical eleven in any one individ- 

 ual becomes very slight. The chance 

 of this complete occurrence in any twO' 

 brothers, not twins, is naturally but one 

 in a number represented by the square 

 of this first number, naturally so large 

 a one as to practically preclude its ap- 

 pearance otherwise than as the result 

 of some genetic principle which must 

 be considered as causal. 



CORRESPONDENCE IN BODILY MEASURE- 

 MENTS 



For many years now this case of 

 the two M s, with its many fea- 

 tures that have to be duplicated, has 

 been my best case, because of the many 

 separate features involved, but recently 

 there has appeared a second case, 

 equally complete, where, too, in addi- 

 tion to the palm and sole prints, there 

 has been obtained a full set of bodily 



measurements. These are the B s, 



students of Smith College, and evi- 

 dently, from the close facial and gen- 

 eral physical correspondence, duplicates. 

 From the tracings, which are here pre- 

 sented, instead of the actual prints, the 

 complete representation of all eleven- 

 patterns is evidently as good as in the 

 other case. 



