It is known that if S be one of a range of conics touching four given lines, and if XP be a variable line through a given point X, then (a) there exists a line p′ which is conjugate to XP with respect to every S, and (b) p′ touches a fixed conic σ, which is the eleven-line conic of X with respect to the range, and which is also the envelope of the polar of X with respect to the range. Let us call this conic the σ of X.