Problem: Identify the form of argument used and evaluate each argument according to the standards for that form. In the outbreaks of human poisoning from methylmercury in Japan and later in Iraq, one of the most consistent signs in adults was deficits in visual function. . . . the visual system of macaque monkeys resembles that of humans and exhibits the same signs and pathological lesions as that of humans when exposed to methylmercury. macaques are therefore excellent models for testing the effects of methylmercury on the visual system.