family tree" (p. 176). He wrote twelve mysteries in total, though their author's identity was unmasked by 1928. The first few books about the distinctive Philo Vance (who shared with his creator a love of art and a disdain for the common touch) sold many copies, leading Wright to become wealthy for the first time in his life. His readership was diverse and worldwide. David Shavit's study of World War II POW reading habits revealed that Vance was one of the favorite detectives among officer POWs. However, according to critic Julian Symons: Wright's later books declined in both quality and popularity. The reading public's tastes changed, and the "hard-boiled" school of detective fiction became the dominant style in the 1930s. The new mood was captured by Ogden Nash in his brief verse: Philo Vance Needs a kick in the pance. Philo Vance and Sam Spade occupy different aesthetic universes. Wright continued to make money, though, and by the end of the decade, he saw himself caught in a trap from which he could not escape: in the midst of the Great Depression, he could not return to literary journalism and art criticism which paid very little, now that he and his wife were accustomed to an extravagant way of life, and yet he no longer believed in the kind of novels he was producing each year in order to maintain that way of life. Study of detective fiction Wright's lengthy introduction and notes to the anthology The World's Great Detective Stories (1927) are important in the history of the critical study of detective fiction. Although dated by the passage of time, this essay is still a core around which many other such commentaries have been constructed. He also wrote an article, "Twenty Rules for Writing Detective Stories", in 1928 for The American Magazine It has been frequently reprinted and compared to "Knox's (Ten) Commandments" by Ronald Knox. Short film series Wright wrote scenarios for Warner Brothers film studio in the early 1930s. These were used as the basis for a series of 12 two-reel "murder mystery" films, each approximately 20 minutes long, which were released in 1931–1932. Of these, The Skull Murder Mystery shows Wright's vigorous plot construction. It features a non-stereotypical treatment of its Chinese characters, something quite unusual in its day. Donald Meek (as Dr. Crabtree) and John Hamilton (as Inspector Carr) were featured players, with Joseph Henabery