After some time, Algernon died because of the experiment(because he was losing his intelligence)
Here lies Algernon 19?? to 19??
After the dead of Algernon, Charlie created the formula called "Algernon Gordon Effect" and that formula makes you lose intelligence if you participate in the operation, so that is happening to Charlie
I should leave town before I get dumb again, I do not what to start everything over again and live that life where i couldn't read or write.
On these scene, Charlie is leaving New York so the people that he show he was intelligent don't laugh at him, he past the graveyard where Algernon was he left a flower