However disposed we may be to restrict the part played by the brain—that is to say the cortical layer—it remains a predominant factor and the final terminus in the process of transmission. Here we plunge into darkness. Researches into cerebral localisation teach us on this subject nothing which is generally admitted. During the first period of such studies, which may be called that of circumscribed localisation _à outrance_, Ferrier placed the seat of the emotions in the occipital lobes, because, in his opinion, that region of the cortex receives the visceral sensations, because the sexual instinct is dependent upon them, and finally, because these lobes are more developed in women than in men. It is needless to bring forward the numerous criticisms of this thesis. During the second and present period of localisation, which may be called that of disseminated localisation, functional rather than anatomical, authors are little inclined to admit a particular centre for the affective life in general, and still less for pain. All the sensory centres, and even all the motor centres (perhaps there are fundamentally only sensori-motor centres with preponderance of one or the other element), may under certain conditions of activity produce in consciousness a feeling of pleasure or pain. The hypothesis of a cortical centre is not, therefore, probable; I shall return to this point in discussing the emotions. II. The modifications of the organism which accompany physical pain have been so often described that it is enough to trace a slight outline of them. They may be reduced to a single formula: pain is associated with diminution and disorganisation of the vital functions. 1. It acts on the movements of the heart, generally decreasing its frequency; in extreme cases the slackening may go so far as to produce syncope. In animals submitted for experiment in the laboratory, even after removal of the encephalon, painful impressions diminish the cardiac contractions. In man, though the frequency of the pulse is sometimes increased in one form or another, there is always a modification of the rhythm appreciable by the sphygmograph. Bichat was right when he said: “If you wish to know whether pain is real, examine the pulse.”