Summary

Abstract

Experimental studies with a microorganism, the protozoan algal flagellate Euglena, have been described in order to indicate how much an organism can be used as a research tool for investigators seeking answers to problems in cell morphology, chemistry, growth, pigment synthesis, photosynthesis, photoexcitation, and other biological phenomena. The uniqueness of Euglena lies in its ability to alter greatly its chemistry and structure depending on its environment, e.g., temperature, chemicals, light ↔ dark. These physical and chemical changes have been studied experimentally from the point of view of relating the structure and the chemistry to their functional physiology. The broad implications of these studies to the problems of light utilization by living systems, such as the molecular structure of the chloroplast to photosynthesis and the eyespot and flagellum to photoexcitation processes, is stressed.