Present knowledge and understanding of the fiber tract pathways and nuclear masses in the central nervous system which have to do with the conduction and integration of respiratory impulses is still somewhat uncertain, in spite of the considerable amount of research that has been done. One of the main obstacles to the solution of this problem has been the inability of workers to produce small localized lesions in experimental animals. Focal lesions of the desired location are of the utmost importance when a variety of functionally different nuclear masses and fiber tracts are crowded together in as small a structure as the brain stem. A large part of the experimental work with animals onthe location of the central nervous respiratory system has involved lesions affecting one third, one half or complete sections of the brain stem. Obviously, these lesions destroy tracts and nuclear masses that have little or nothing to