Here are things upon which I ruminate. The rumen is the first stomach of a ruminant. Cows chew their cud, pass it to the rumen, where it is digested with the aid of bacteria and enzymes, and then passes to the reticulum. Reticulum is the name of a small, vague constellation in the Southern sky. Reticulum is from the Latin for a small net or reticle. A reticle is the fine crosshairs in the eyepiece of a telescope.