Gertrude Atherton 
Black Oxen [EPUB ebook] 

Lee Clavering (Tearle), a playwright in New York, falls in love with an Austrian countess, Madame Zatianny (Griffith). Janet Oglethorpe (Bow), an animated and precocious flapper, is also in love with Lee but he hasn't noticed yet. Unbeknownst to Lee, Madame Zatianny is actually 58 years old, and has retained her youth through a rejuvenating glandular treatment and X-ray surgery. Lee's plans to marry Madame Zatianny are thwarted when one of her former admirers reveals her embarrassing secret and, in the end, Lee discovers happiness with Janet.