the "ultimately lethal" program developed by morris had 44 instructions, and employed an adaptive strategy. once it successfully located the start of an enemy program, it would probe some small distance ahead of this location. if it succeeded in killing the enemy, it would remember the distance and use it on subsequent encounters. if it instead hit a protected location, then the next time it gained control it chose a different distance. any new copies were initialized with a successful value. in this way, morris's program evolved into multiple subspecies, each specifically adapted to kill a particular enemy.