Mydriasis iris sphincter, composed of circularly arranged muscle fibers, and the iris dilator, composed of radially arranged muscle fibers. The sphincter is innervated by (signaled by nerves of) the parasympathetic nervous system, and the dilator by the sympathetic nervous system. Sympathetic stimulation of the adrenergic receptors causes the contraction of the radial muscle and subsequent dilation of the pupil. Conversely, parasympathetic stimulation causes contraction of the circular muscle and constriction of the pupil. The mechanism of mydriasis depends on the agent being used. It usually involves either a disruption of the parasympathetic nerve supply to the eye (which normally constricts the
What Is a Nation? often adopted the religion and manners, and married the women, of the people they conquered. He notes that France was quite ethnically diverse during the French Revolution. For example, "at the end of one or two generations, the Norman invaders were indistinguishable from the rest of the population". Nonetheless, they had a profound influence, bringing with them "a nobility of military habit, a patriotism" which did not exist before. - Renan then states what has become one of the most famous and enduring ideas of the essay. "Forgetfulness, and I would even say historical error, are essential in the creation