What is Tony forced to do when he stands trial for Ganter's murder in the novel, East Indian?

When Tony stands trial for Ganter's murder, he is made to touch Ganter's body and informed that if Ganter's blood rises to his touch it will mean that Tony was the murderer. The silliness of this evaluative method enrages Herman, but it also conveys the utter lack of knowledge that most of the people in the colony possess about modern medicine.