IN experiments upon paths of nervous conduction in the mammalian spinal cord, departures, both numerous and wide, from the "Fourth Law" of Pfluger have been recorded by one of us'. Pfluiger's "Fourth Law " runs: " Reflex irTadiation in the spinal cord spreads upwards or anteriorly, i.e. towards the medulla oblongata2." Contrary to this statement, there certainly exist many spinal paths by which the activity aroused in spinal segments situate nearer the head is commtunicated to segments lying fuirther backward. The present paper results from search for more detailed evidenice regarding aborally-running reflex spinal paths. The above quoted "law" of Pfluiger is usually accepted and endorsed without comment, but physiological literature records here and there examples of spinal reflexes irradiating aborally. Thus: the