These are more scrupulously informed and effortlessly narrated case histories, New Yorker based in origin while the field work ranges all over the country. As Mr. Roueche's admirers know by now -- this is the eighth collection -- there will be peculiarities if not rarities such as the Orange Man whose pigmentation was finally attributed to too many carrots and too much tomato juice; or the perplexing Epidemic neuromyasthenia which seems to favor young women in cloistered situations. Those currently alarmed at the mercury content in fish might remember also the high toxicity of the Huckleby Hogs. Then there was the nationwide notoriety of the Salmonella outbreak at Massachusetts General Hospital. Common indeed are some intractable hiccups which tortured an elderly man and had their origin in a sulfonamide, or the ""Shiver and burn, tremble and die"" malaise of a young bride -- malaria. This gives Mr. Roueche a chance to review the long history of this endemic disease. As always he has precisely charted his cases from puzzling effects to equally puzzling causes. It is a genre he has just about perfected.