China held its second-ever National Constitution Day on Friday, when citizens are supposed to renew their loyalty to the Constitution that both enshrines the Communist Party’s power and promises freedom of expression and other rights — so long as that power is not challenged.

The limits of those freedoms have been underlined by the disappearance from many bookstores of a new book about China’s tortuous history of constitutional transformation by one of the country’s pre-eminent historians.

The book, “Out of Imperialism,” by Qin Hui, a professor at Tsinghua University in Beijing, has garnered considerable attention since it appeared this fall. Mr. Qin is a well-known thinker with liberal views, and there was an avid readership for his book, an examination of how China broke free from the Qing imperial order only to see the promise of constitutional democracy fall apart in the early 20th century.

“It has sold quite well,” said a cashier at Sanlian, one of Beijing’s most popular bookstores. “But several days ago we were told not to sell it anymore, so the books are all gone now.” The cashier would not give her name or say who issued the directive.

Mr. Qin, who confirmed that his book was pulled from stores, said by telephone from his home in Beijing, “I don’t want to talk about it right now.” ...