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The Journal of Heredity 



ures used here were twice copied. The 

 fact that in the second twin the same 

 number, 530, is also given as the acro- 

 mial height, and occurs on the list im- 

 mediately beneath it, suggests such an 

 error as an easily explained possibility. 



CLOSE IDENTITY IN PHYSICAL 

 STRUCTURE 



Taking, now, the figures directly from 

 the tables, there are some very strik- 

 ing similarities, amounting in a few 

 cases to complete. or practical identity. 

 Thus, starting with a total stature of 

 1,668 and 1,669, we find the height of 

 the vertebra prominens and that of the 

 incisura sterni the same exactly, while 

 the height of the tragus has but a single 

 millimeter of difference. The heights 

 of the very mobile shoulder girdle and 

 of the parts of the arm depending from 

 them, as already explained, cannot be 

 expected to be constant, but the 

 length of the arm and its parts in the 

 two, as obtained by subtraction of 

 heights from one another, is very close. 

 As for breadths, the biacromial differs 

 by but 3 mm., the cristal, across the 

 hips, by 1, and the trochanteric not at 

 all. In thoracic measures we have 

 232 X 175 and 236 x 175, where the 



4 mm. difference in one dimension 

 alone is negligible. The length and 

 breadth of the two heads is identical in 

 both twins, 185 x 142, and it is also 

 significant that the facial measurements 

 show so close a similarity. The few 

 measurements of the soft parts, the 

 nipples and the umbilicus, are of minor 

 importance, as they do not depend upon 

 a bony support and are easily change- 

 able. Taken in general, there is a sur- 

 prising degree of identity in the bodies 

 of these twins. 



This test of bodily measurements 

 offers an important field in the inves- 

 tigation of twins. They should be 

 measured while young, before the 

 varied experiences of after life have 

 effected much modification, but after 

 maturity is reached. It would be also 

 of interest to get several series of such 

 measurements of the same sets of 

 twins during growth, from infancy to 

 maturity. From such studies could be 

 learned, for instance, the effect of va- 

 rious illnesses undergone by one twm 

 and not the other, and in such things 

 could be found explanations for many 

 of the slight lacks of complete corre- 

 spondence which are out of harmony 

 with what would be expected in gen- 

 uine duplicate twins. 



0(^0 



D-^OOO 



