THE EFFECT OF WHITE LIGHT UPON THE RATE OF DEVELOPMENT OF THE RHIZOID PROTUBERANCE AND THE FIRST CELL DIVISION IN FUCUS FURCATUS

Abstract

Developmental rates of 2,000 eggs in populations thinly spaced to avoid certain mutual effects were measured at 14 3/4[degree] C. The time lapse from fertilization until 50% of a population developed early rhizoid protuberances was approximately 14.0 hrs. in white light (1500 ergs/sec./cm.2) and 17.8 hrs. in the dark (28% longer). The cell plate formed at 21.9 hrs. in the light and 25.0 hrs. in the dark. White light thus markedly speeds up the formation of the rhizoid protuberance, and most of the gain holds to the first cell division. One percent dextrose in the medium did not appreciably affect the rate of protuberance formation.[long dash]D. M. Whitaker.