SOLE PATTERNS OF TWINS. 



ROBERT B. MONTGOMERY, B.S., M.D., 

 INSTRUCTOR, DEPT. OF CLINICAL MED., UNIV. OF Wis. 



In the study of twins, one frequently desires to know whether 

 or not they are of monozygotic or dizygotic origin. This question 

 can be answered by examination of the placenta and membranes 

 at birth, but when older children and adults are studied it is 

 difficult, and often impossible, to do so. Work has been done 

 on the general physical appearance, mentality, palm patterns, 

 whorls of the hair, etc., but no definite data has been secured. 

 This study was undertaken in the hope that the friction-ridge 

 patterns on the sole of the foot might reveal some clue as to the 

 type of twin from whom they were secured. 



Newman ] 2 thinks that monozygotic twins are apt to have 

 identical patterns, that they are found nearly always in this 

 type of twin, but that unlike patterns do not disprove their 

 monozygotic origin. Wilder 3 also has remarked upon the 

 striking similarity which sometimes occurs. He 4 states that 

 while they are similar grossly, the Galton details are always 

 different. Accurate information on this subject is lacking. 



Prints were secured from 87 pairs of twins living in Madison 

 and vicinity ; the process perfected by Professor Mathews being 

 used in order that the fine details might be more readily studied. 

 The youngest pair was one week old, and the oldest 85 years. 

 Most of the subjects, however, were school children. Thirty- 

 three pairs were male-male, 24 were female-female, and 30 were 

 male-female. Of the 174 individuals examined, 96 were male 

 and 78 female. 



The ratio of monozygotic to dizygotic twins has been variously 

 stated. Newman : thinks that the monozygotic type occurs 

 about 25 per cent, of the time, while De Lee 5 quotes Ahlfeld 

 as stating that 15.55 P er cent, of all twins are monozygotic. 

 Ahlfeld's figures are, perhaps, more reliable because he examined 

 the placentas and membranes in 1,157 twin births. 



The Wilder method is used in classifying the patterns and 



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