1. A method was found whereby the development of gastric retention could be studied in intact animals without the necessity of recourse to the use of x-rays.
2. Gastric retention was found to develop as a result of protein restriction in 7 out of 10 rats studied. Such retention could again be cleared up with protein realimentation or by allowing the animals free choice of protein, fat and carbohydrate.
3. A diet high in protein following periods of undernutrition or prolonged protein restriction usually gave rise to a transient gastric retention.
4. Diets with a solution of 25 per cent or more of alcohol added promptly gave rise to gastric retention in rats even when the protein content of the diet was adequate.
5. Evidence is given indicating that the gastric retention which occurred in this study involved more or less pylorospasm and the possible influence of mechanical and chemical irritation and of changes in gastric mucin and bile flow upon the development of pylorospasm are discussed.
6. Spira's theory that fat in the diet gives rise to pylorospasm and ulceration is not supported by the results of our experiments.