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? what Lenin’s real views were". Therefore, Lih argues, the word спонтанность, when translated as "spontaneity", distorts his views and has different contextual connotations; how конспирация does not mean "conspiracy", but "the rules and procedures needed for an underground organisation to survive"; тред-юнионизм does not mean "trade unionism", but non-revolutionary "only trade unionism"; and революционер по профессии should not be translated as "professional revolutionary". What Is to Be Done? What Is To Be Done? Burning Questions of Our Movement () is a political pamphlet written by the Russian revolutionary Vladimir Lenin (credited as N. Lenin) in 1901 and published in 1902.