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January 1930


Arch NeurPsych. 1930;23(1):114-129. doi:10.1001/archneurpsyc.1930.02220070117006

It is a generally accepted theorem today that the nervous apparatus of higher animals is constructed on the plan of a pyramid of levels or systems through the erection of increasingly more complex organizations superimposed on the simpler, and that many of these levels probably indicate major phylogenetic progressions. Thus, one recognizes the parallelism between the asynaptic net of the mammalian intestines and that of Medusa, between the ganglionated cord of the sympathetic nervous system and that of the crustacea, between the spinal cord and the equipment of the amphioxus and between the midbrain centers of mammals and the "brain" of the lower fishes, birds and reptiles. In each animal the completed nervous structure of which represents one of these levels one, of course, finds a path of translation from the sensory or receptive mechanism to the motor or effector group. It is a principle of the pyramiding by which