84 Society for Experimental Biology and Medicine. 



piration ceased till it was thoroughly re-established after resusci- 

 tation. 



Result. — An interval, varying in length with the duration of 

 the occlusion and other circumstances, was found during resuscita- 

 tion, when spontaneous respiration had returned and was going on 

 with a regular rhythm while totally incapable of being influenced 

 by stimulation of any of the afferent paths investigated. The most 

 probable assumption is that at this stage some portion of these 

 afferent paths to the respiratory center was still unable to conduct 

 impulses to the center, the block being possibly (in terms of the 

 neurone hypothesis) in the synapses in which the afferent fibers 

 terminate in the bulb. Resuscitation of the center and the efferent 

 paths from it had at this stage been carried to the point at which 

 the motor impulses were able to pass down to the anterior horn 

 cells which innervate the muscles of ordinary respiration. If at 

 this point in the resuscitation the afferent paths of the vagus and 

 the brachial plexus are still interrupted, it is reasonable to assume 

 that the same is true of the other afferent fibers connected with the 

 bulbar respiratory center. For certainly of the fibers running 

 headwards to the bulb none can be supposed to be more favorably 

 situated for carrying impressions to the respiratory center than the 

 afferent fibers of the vagus. Nor can it be imagined that at this 

 time impulses can be passing to the center from the higher parts 

 of the brain, since it is a general rule that the nervous structures 

 higher than the bulb require a longer time for resuscitation than 

 the bulb or the spinal cord does. 



Conclusion. — The method described seems indeed to afford, 

 what has long been a desideratum, a means of temporarily elim- 

 inating all the afferent paths connected with the respiratory center. 

 Since under these conditions the center continues to discharge 

 itself in such a way as to maintain a long and unbroken series of 

 regular, efficient respiratory movements, its normal activity is to 

 be considered an example of physiological automatism, not orig- 

 inated, although influenced by afferent nervous impulses. 



