Summary.1). Food selection both qualitatively and quantitatively is the chief regulatory action in preserving the integrity of the organism in relation to the external milieu.2). Theneedfor food has been called starvation, hunger, thirst, special hunger etc. The same concept has been used to indicatedesirefor food. The author wishes to introduce a more closely defined terminology by sharpening the difference between theneedof foodstuffs and thedesirefor foodstuffs. The former implying that certain forms of luxury consumption are here ignored, — the necessary presumption for the rise of the latter.3). Experiments have already been made which indicate that in the animal organism certain desires for food of different kinds arise, corresponding to the need for the different foods. Thus, “hunger” is a collective concept which can be resolved into a whole series of needs for food with corresponding desires for food, leading to different food selection for the satisfying of the different needs. Thus “thirst” is desire for H2O. The author proposes that in the scientific literature of this subject the word “hunger” should be reserved for the desire for calories, which arises when a supply of energy is needed.4). The discussion of the mechanism of the desire for food, general feelings, sensations of taste, instinctive impulses is postponed until the author presents his observations in later communications.5). The method used by the author for the measuring of food selection by animals — rats, mice and guinea‐pigs — is described in detail. The interpretation of the quantitative facts obtaine