After the solution catches the c 2 -nullcline it slides down the c 2 -nullcline as it approaches the origin (see, Movie 2 in Supplementary Materials). We refer to this manifold as a Laelaps manifold after the Greek mythological dog that always caught what she was hunting. Analogously, the solution to the mass action equations "hunts" the moving the c 2 -nullcline (see Figures ).