The establishment of a self-perpetuating animal association in an environment that is abiotically uniform appears to be essential for ascertaining and understanding the principles of biotic regulation of populations. If this association so established is of a simple type, such as that of a plant-feeding insect under regulation by one of its natural enemies, the isolation of basic regulatory factors and a study of the operation of each, free of the extraneous or secondary factors which confuse relationships under natural conditions, is possible.
