Evolution of the distribution of perihelion distance a), semi-major axis b), eccentricity c), argument of perihelion d), longitude of ascending node e), and inclination to the ecliptic f) for the part of the C/1917 F1 stream modeled at a time 40000 years before the present. The bottom curve in each plot shows the initial distribution of a given element. Each successive curve, which is entirely shifted vertically about a small displacement above the previous one, shows the distribution after another 1000 years. The top curve shows the distribution at the present.