It is important for the physiology of secretion as well as for the study of conditioned reflexes to understand the relation of quantity of salivary secretion to the amt. of food. In 12 normal dogs having chronic parotid fistulae a study was made of the amt. of saliva secreted to weights of food varying from 0.75 g. to 40 g. In all of the animals the secretion begins at a considerable distance [alpha] above zero: the curve of secretion is a straight line whose formula is S=a+bQ where a and b are constants for each dog and S and Q are the amounts of saliva and food respectively. If the secretion is reduced to per gram of food per kg. body weight the secretion for all the animals plotted with food and secretion as coordinates is a hyperbola whose formula is S1=k 2/Q + k 2 where k1 and k2 are constants independent of the dog and of the temperament, age, sex, etc. The hyperbolas for all the dogs coincide, showing that the secretion is practically equal in any dog when reduced to unit kg. body weight. A similar formula to that governing the relation between food and secretion holds for duration of eating (mastication and deglutition) and secretion, when the amount of food varies, viz., S=a 1 + b 1 t where S= secretion, a1= a constant (the minimum secretion), and b1 = a constant, ds/dt; i.e., the time required for the dog to eat the food is proportional to the amt. of food. The secretion for a fixed amount of food is independent of the length of time required to eat the food. An analysis of the factors having to do with the value of a in the formula S = a + bQ are given. The conditioned and unconditioned reflexes are roughly parallel. An initiation of the unconditioned reflex inhibits the action of the conditioned reflex[long dash]there is no summation of the unconditioned and conditioned reflexes similar to the summation of allied segmental reflexes nor to the summation of 2 similar conditioned reflexes.