THE NERVOUS MECHANISM OF RESPIRATION OF THE SELACHII

Abstract

Historical Survey Experimental Methods Experimental Results Normal Respiration Pressure of Respiratory Currents The Effect of Drugs Stimulation of Body Areas Transections and Stimulations of Cranial Nerves Transections of Brain Transection of Spinal Cord Transection of Dorsal Roots of the Spinal Cord Comment Summary The problem of the respiratory mechanism of vertebrates has not been worked out completely in any group. In mammals, considerable progress has been made, but the subject is so complex that it is difficult of analysis. If the evolutionary history of this complicated mechanism were known, many unsolved phases of the problem might be made easier of approach. This knowledge would also be useful in furthering an understanding of natural selection and adaptation. Physiologists and neurologists have long disputed whether functional relations within the central nervous system have changed during the course of evolution or whether evolution has come about through the further elaboration, or dropping out