We also wondered how the number of B-M scaffolds increased with the number of heavy atoms (Figure ). We plotted both the cumulative number of scaffolds with each additional heavy atom as well as the incremental number of scaffolds added with each additional atom. In the "fragment-like" range of 10 to 16 heavy atoms, each additional atom increases the number of B-M scaffolds by between 2-and 3-fold. In the small-lead-like range, this drops below 2-fold, and among the largest lead-like molecules (24-25 heavy atoms) it falls still further to about 1.2-fold growth in scaffolds with one additional atom. Although the trend in the ratio of new scaffolds with each additional atom is seen as generally declining, the extact trend remains unclear.