Flatworms possess excretory organs known as nephridia. Specifically as annelids, flatworms possess a variant known as metanephridia.
A little more context would be helpful, but in general Gram Staining helps us to decipher between two major groups of bacteria (Gram positive and Gram Negative). This is helpful because different antibiotics must be used to treat infections from the different types of bacteria, so it will help them to properly medicate Anna.
This invention was a commercial failure. Edison resolved that in the future he would only invent things that he was certain the public would want. ... This gave Edison the money he needed to set up his first small laboratory and manufacturing facility in Newark, New Jersey in 1871.
found at: https://www.nps.gov/edis/learn/historyculture/edison-biography.htm
