In 1845 Dowler began a series of experiments in comparative physiology on the alligator of Louisiana, which led him to conclude that, after decapitation, the head and, especially, the trunk afford evidences of possessing the faculties of sensation and motion for hours, and that the headless trunk, deprived of all the senses but that of feeling, still retains the powers of perception and volition, and may act with intelligence in avoiding an irritant. As the result of those discoveries, he held that the functions and structure of the nervous system constitute a unity inconsistent with the assumption of four distinct and separate sets of nerves, and a corresponding four-fold set of functions.
