The importance of this discovery may be gathered from the fact, that but few considerable advances in the physiology of the nervous system had hitherto been made, the most important being that of Sir Charles Bell, proving that there were separate nerve fibres of motion and of sensation, and that they entered different portions of the spinal cord and brain. Dr. Andrew Whytt of Edinburgh had published in 1751 a work in which he detailed the movements which a frog’s trunk was able to execute after its head had been cut off, and had naturally referred these movements to the spinal cord; but the import of such actions was not understood, nor the mechanism by which they were executed. Somehow these observations led to no new principles. But the truly original mind of Marshall Hall travelled beyond the first facts to trace the process, and he at last comprehended the nature of such acts as the involuntary closure of the eyelids, independent of will, for the purpose of preventing the admission of injurious matter, or of protecting the eye against injury. The processes of swallowing, choking, vomiting, coughing were now for the first time explained. Further, in pursuance of Marshall Hall’s practicality of object, many cases of injury to the nervous system became more or less intelligible. In paralysis of the brain, where the medulla oblongata and spinal cord were uninjured, it was understood how the animal functions could be maintained, and how in cases where the patient was unable by any exercise of the will to clench his hand, yet the stimulus of a rough stick on the sensory nerves of the palm of the hand was sufficient to bring about a forcible grasp, this being a simple reflex act in which the spinal cord was concerned. The first breath of a new-born infant, the spasmodic closure of the larynx in convulsions, fits of spasmodic asthma, &c., were seen to be reflex in their nature; and in many disorders which had hitherto baffled curative efforts, they became possible, because the first great step had been taken, the understanding of the phenomena.