 DATE: Johnny says to Amsterdam that Bendrick the Cockroach "carries  a germ" and that "if you try to leave the gang, they say, he hacks  up blood on you." Germs werent understood as causing disease until  after Robert Kochs 1876 publication; Louis Pasteurs work, also  published in the 1870s, completed the proof to the medical  community. But as late as 1914 it was still referred to as "the germ  theory of disease". In the 1860s no ragamuffin street kid would have  made the connection. He wouldnt have used the word that way,  either; the first recorded use in medical literature is John  Tyndalls 1879 Fragments of Science for Unscientific People. Until  then, "germ" just meant that part of a seed from which the plant  sprouts.