Sentence:  For any pencil in a plane <WSD>containing</WSD> a * * f-fold secant of \ g has an image regulus which meets the plane of the pencil in * * f lines , namely the images of the lines of the pencil which pass through the intersection of \ g and the multiple secant , plus an additional component to account for the intersections of the images of the general lines of the pencil . 
Meaning of the word marked with <WSD> tags:  include or contain; have as a component