In this chapter, in particular, there is one error in vocabulary on page 14. On the right column it describes what Robert Johnson did in New Jersey. In two places it is called an experiment. This fellow ate a lot of tomatoes. That would be a manipulation.
Experimental science demands control with the manipulation.
Obviously he needed to do some testing before subjecting himself to a suspected toxin. Perhaps he could have fed the tomatoes to 10 rats along with their regular feed and given just regular feed to 10 other rats. I hope you have learned a little bit about better science here.