Milton Marx was born on 23 October 1892. Like his older brothers, he flirted with the stage in early life, but soon realisd it wasn't for him.

During the brothers' film heyday, he was in the ladies' clothing business.

Later, when Zeppo had stopped appearing in the films, Gummo teamed up with Zeppo to manage the three brothers, and he represented them long after they stopped working together.

While not a performer, Gummo appears to have retained the customary Marx wit. Once when Groucho, becoming philosophical over lunch, mused that "there are really two Groucho Marxes", Gummo replied, "Oh yeah? How come I'm only getting commision from one?"

He died in 1977, just months before Groucho.

Sources :

Groucho, Harpo, Chico and sometimes Zeppo, Joe Adamson

Monkey Business - the lives and legends of the Marx Brothers, Simon Louvish