Exhibit A is my favorite photograph of the director, actually taken with Bow on the set of The Wild Party (1929), their second collaboration and Bow's first talkie

And for which, according to legend (and fairly credible reports), Arzner invented the boom mike to allow Clara Bow to move around on set (whereas previously actors had to stay very close to where their microphone was placed):

http://www.smithsonianmag.com/smart-news/1920s-dorothy-arzner-paved-way-female-directors-today-180955904/