This experiment was conducted with 112 young children of four, five and six years of age. The following eight areas, were involved : the counting of the numbers, the ascertaining of the numbers of real objects, the selection of the equal numbers with the presented objects, the comparison of the type 'more' or 'less', the selection of the requested numbers, the dividing of the numbers, the combination of the divided numbers, and the change of the orders of the numbers. Experimental results indicate that the development of the conception of numbers is done through the dialectical reciprocal action of the two notions, that is, the notions of quality and order, and at the same time, the phase of the reciprocal action characterizes each developmental stage in the process of escaping from the perceptional impression of the objects. The following six stages are discerne in the early months after entrance into the primary school. 1st stage the period when the two notions of both quality and order are very far separated from each other. 2nd stage the period when the notion of quality takes the governing role over the notion of order in the reciprocal action of the two notions. 3rd stage the period when the notion of order is strengthened while the notion of quality retreats backwards for a while. 4th stage the period when the notion of quality is strengthened in reverse, while the notion of order retreats backwards. 5th stage the period when the unity of the two notions of both quality and order becomes unstable. 6th stage the period when the unity of the two notions of both quality and order becomes stable.