To remember the history of "pullulate," think chickens. This may sound like odd advice, but it makes sense if you know that "pullulate" traces ultimately to the Latin noun pullus, which means not only "sprout," but also "young of an animal" and, specifically, "chick." "Pullus" is also an ancestor of "pullet" ("young hen"), "poult" (meaning "young fowl" and especially "young turkey"), and even "poultry" ("domesticated fowl"). At first "pullulate" referred to sprouting, budding, and breeding around the farm; only later did it gain its "swarm" sense.