text: DelbrÃ 1\/4 ck was born in Berlin , German Empire .
simplified: During the 1940s DelbrÃ 1\/4 ck developed a course in bacteriophage genetics at the Cold Spring Harbor Laboratory to encourage interest in the field . In 1947 , DelbrÃ 1\/4 ck returned to Caltech as a professor of biology where he remained until 1977 .