Iris sphincter muscle Iris sphincter muscle The iris sphincter muscle (pupillary sphincter, pupillary constrictor, circular muscle of iris, circular fibers) is a muscle in the part of the eye called the iris. It encircles the pupil of the iris, appropriate to its function as a constrictor of the pupil. It is found in vertebrates and some cephalopods. Initially, all the myocytes are of the smooth muscle type but, later in life, most cells are of the striated muscle type. Its dimensions are about 0.75 mm wide by 0.15 mm thick. In humans, it functions to constrict the pupil in bright light (pupillary light
What Is to Be Done? (novel) Is to Be Done?" is one of the sources of inspiration for Rand's thought. For example, the book's main character Lopuhov says "I am not a man to make sacrifices. And indeed there are no such things. One acts in the way that one finds most pleasant." Vladimir Nabokov's final novel in Russian, "The Gift", ridicules "What is to Be Done?" in its fourth chapter. What Is to Be Done? (novel) What Is To Be Done? (; also translated as What Shall We Do? and literally translated as "What To Do?") is an 1863 novel written by the Russian philosopher,