''If the old cells inoculated in chicken, it produces resistance in the chicken against new V. cholera cells.''
Explanation:
From the data provided by Louis Pasteur, we make a hypothesis i. e. ''If the old cells inoculated in chicken, it produces resistance in the chicken against new V. cholera cells.'' From these observation we can assume that by allowing old V. cholera cells to chicken, it did not cause any disease but make immunity against the new V. cholera cells which are more effective from old V. cholera cells.
A mutagen changes the level of mutations that occur in the DNA either by affecting it physically or chemically. This helps researchers create different organisms with altered phenotypes according to what the research needs so that the genes can be investigated further under a controlled environment.