There can be no doubt that hunger is one of the most fundamentally important experiences in the life of every organism, and that it is a factor which has played a dominant part in the history of Man, and indeed of all animals, cannot be denied. No subject could be more profitably surveyed since its influence involves such vital issues. Despite the fact that hunger is so universal a problem one must admit that, compared with other questions arising in connection with our existence, the matter has received comparatively scanty attention. This state of affairs is due possibly to the fact that hunger, as a sensation,is hard to analyse since its disagreeable effect on consciousness induces other conflicting elements of an emotional nature so that a logical study of the already complex process is rendered more difficult. If hunger, regarded in its wider sense, does occur in animals it is probable that in them, lacking as they do the higher cerebral centres, the sensation is less complicated than in man, but, for obvious reasons, the study of the problem in them must be limited largely to objective phenomena secondary to hunger.