text: DelbrÃ 1\/4 ck 's efforts to promote the `` Phage Group '' ( exploring genetics by way of the viruses that infect bacteria ) was important in the early development of molecular biology .
simplified: DelbrÃ 1\/4 ck 's big idea was to explore genetics by means of the bacteriophage viruses which infect bacteria . This was important in the early development of molecular biology .