A Rutgers University evolutionary biologist says that a presentation he was scheduled to give at Harvard University on Friday was canceled after he said in a letter to The Wall Street Journal that Alan M. Dershowitz, the Harvard law professor, was a “Nazi-like apologist” who needed “to be confronted directly.”

The Rutgers professor, Robert L. Trivers, had been invited to speak at Harvard and planned to discuss his research into self-deception and how it factored into Israel’s decision to invade Lebanon in 2006, according to The Boston Globe. He was told on Friday morning, however, that the talk had been canceled.

His letter to the Journal was a response to an earlier letter in which Mr. Dershowitz again attacked Norman G. Finkelstein, an assistant professor of political science at DePaul University (The Chronicle, April 13). Mr. Trivers wrote: “Regarding your rationalization of Israeli attacks on Lebanese civilians, let me just say that if there is a repeat of Israeli butchery toward Lebanon and if you decide once again to rationalize it publicly, look forward to a visit from me. Nazis — and Nazi-like apologists such as yourself — need to be confronted directly.”

Mr. Dershowitz told the Globe that he had alerted the Harvard police to what he considered to be a threat. But he said he had not sought to have the talk canceled. Mr. Trivers said he had not meant to threaten Mr. Dershowitz physically. —Lawrence Biemiller