by Stan Zahler
When you streak out Your Favorite Bacterium on an appropriate agar plate, the colonies reach an expected diameter and stop growing. Why?
Corollary: If you inoculate YFB in the center of an agar plate and incubate it, it would reach its expected diameter. What do you predict would happen if you touch the tip of a sterile hair to the edge of the colony, draw it out on the agar radially, and re-incubate the plate?