ONE of us1–4 has already established that amorphous surface layers have a persistent character which can manifest itself in the oriented crystallization of material on top of them. The part played by these amorphous interfacial films in the transmission of structural information is not understood: it is not known whether they act merely as an inert intermediate medium or whether they themselves provide an informational net. If the latter is the case, it needs to be clarified whether the informational net exists only when constant contact between the interfacial film and the active surface of the underlying solid is maintained or whether it persists irrespective of the surface which created it.