1. Description of an identical, concordant, deaf mute twin suffering from a perceptive deafness. In the family there occurs no more deafness, on the other hand there are many twins, both M T and D T among their relatives.
2. Description of an identical, concordant, “hearing mute” twin. Up to their eigth year they did not talk at all, they learned speaking when they made their entrance into the Institute for deaf-mutes. They are feebleminded. A brother speaks badly and is slow in intellect too, three cousins of their mother were idiotic.