AN ANALYSIS OF THE MOLTING PROCESS IN THE FIDDLER CRAB, UCA PUGILATOR

1. A transitional series of color changes which occurs during the premolt period of normal animals is described. These changes have been arbitrarily assigned to five stages and the duration of each stage measured. The last four of these are associated with hypodermal activity anticipating ecdysis.2. The inorganic constituents of normal and destalked animals are compared for the premolt and postmolt condition.3. Certain physical aspects of ecdysis are treated in a quantitative manner. These include the absorption of water and dimensional changes.4. The results suggest that the sinus gland-X organ complex plays a role in the regulation of water metabolism and in the metabolism of inorganic constituents.5. Evidence is presented for a diurnal rhythm of water-uptake under the control of the sinus gland-X organ complex.6. The possibility that molt and dimensional increase are separate factors under certain conditions is discussed.