Abstract:
The incorporation of radioactivity into chitin of the exoskeleton after injection of glucose-1-C14 into the blood of a shore crab, Gaetice depressus, was studied in relation to chitin synthesis at stages of the molting cycle.The ratio of chitin to organic matter was determined to be 67.9% in the completed exoskeleton, but different in each cuticle layer; that is, 22.4% in the exocuticle, 74.9% in the endocuticle, and 63.3% in the membranous layer.During the period of endocuticle formation, the radioactivity was rapidly incorporated into chitin within several hours after the injection of glucose-1-C14, while that in blood decreased correspondingly.Throughout the molting cycle, the highest value of incorporation within 24 hours was shown at one day after molting suggesting that the most active synthesis of chitin occurs at the beginning of endocuticle formation and slows down thereafter with the lapse of time.
