TWINS AND HEREDITY 483 



situation. Moreover, we have found that, in identical twins, the more 

 alike they are physically, the more alike they are mentally. These 

 studies tend to show one thing most clearly, that there is no distinction 

 as to heredity between physical and mental characters. 



A great many reports have come in from clinics all over the world 

 concerning cases of identical twins in which both show rare and 

 peculiar physical anomalies. Only a few examples can be given out of 

 a large number that lie before me: 



Bruce and Daugherty report seven cases of identical twins both 

 afflicted with the same form of diabetes mellitus. Kelly Hale reports a 

 pair of twins both afflicted with congenital dislocation of the hips, 

 one wifti left hip dislocated and right eye crossed, the other with right 

 hip dislocated and left eye crossed. This is a case of pronounced 

 mirror-imaging and shows an unusual association of characters. 

 Meierowski reports a striking case of identical twins, both with uni- 

 lateral strabismus, one with right eye badly crossed and the other with 

 left eye slightly less crossed. Croon reports a case of a pair of identical 

 twins who began menstruation on the same day, were normal until 

 thirty, then suffered alike from menstrual difficulties. Both had 

 menopause at fifty, and three years later both developed the same type 

 of carcinoma of the uterus. Von Verscheur reports a striking case of 

 inguinal hernia (rupture) in a pair of elderly twin men, in which the 

 rupture appears on the right side of one and the left side of the other. 

 Goldstein and Schenck report an unusual case of dwarfism in twins. 

 The smaller of the twins was smaller in all organs on one half of the 

 body, a case of hemihypertrophy. Ahfeld reports seven cases of twins 

 in which similar bodily malformations were present in both members 

 of a pair. D'Outrepont reports a case of twins of which both had 

 spina bifida and both had six fingers or six toes on each limb. Leh- 

 mann reports cases of twins both afflicted with cerebral hernias and 

 hypospadias. Davis reports six cases of hare lip and cleft palate pres- 

 ent in both members of the twin pairs. Parker reports two cases of 

 twins both of whom developed dementia praecox, at nearly the same 

 age. Bradley reports several cases of twins both afflicted with similar 

 forms of manic depressive psychoses. Gesell reports twins who both 

 showed extraordinary precosity, who sat up at six months, walked and 

 talked at eleven months, learned French at three years, and were in 

 the seventh grade at the age of nine. 



No one has ever taken the trouble to get together all the data re- 

 ported by observers of twins. If we had all this information together 



