This paper presents theoretical implications of the study of a hospitalized fifteen-month-old infant. Atresia of the esophagus and creation of a fistula for feeding led to deterioration of the relationship of mother and child. Marasmus and depression resulted. Good object relations developed in the hospital. After this a reaction of depression and withdrawal could be elicited at will by confronting the child with a stranger. The authors look for basic biological patterns which are the Anlagen of psychological depression. One pattern is considered to be the reduction of activity and husbanding of energy when confronted by the threat of exhaustion. This can become an ego pattern and is considered a signal function similar to anxiety. This is activated and heightened by repeated disappointments in the symbiotic relationship with the mother. A second basic pattern for depression is based on Benedek's concept of the 'depressive core', with its biological source in alimentation.