According to transmission accounts, causation involves the transmission and propagation of marks or conserved quantities (Salmon 1984, 1994; Dowe 1992). The most influential form of this view holds that two causal processes causally interact when they intersect in space-time and exchange some amount of a conserved quantity, such as mass. On this view, causation is local (the processes must intersect) and singular (it is fully instantiated in particular causal processes), though the account relies upon laws of conservation (Hitchcock 1995).  Although this view inspired many of the new mechanists, and although it shares their commitment to looking toward science for an account of causation, it has generally been rejected by new mechanists (though see Millstein 2006; Roe 2014).