It's initially disappointing when the manic imagination of The Fan Man and Dr. Rat turns to juvenile fiction (there have been picture books) and produces this campy, Boy's Life dream of Darkest Africa. We depart from early-this-century New York in the company of young Charles, Dr. Pickett, his father, and the noted paleontologist Sir Henry Turnbull whose feud with a witch doctor has left him with a lyconthropic hangover. In short, Sir Henry can't help turning into a leopard. Only Charles knows how to break the spell and does so just in time to keep Sir Henry from becoming part of a wild animal act in the Handy Circus. Fortunately Kotzwinkle has something more in mind than nostalgia; his Africa is floridly trippy (""Charles felt as though he were in the garden of a mad giant"") and the spells are truly magical--there's a spirit python with sclaes that sparkle like diamonds, and Turnbull's passage from leopard to human occurs, breathtakingly, before our eyes. Kotzwinkle performs with Ã‰clat, though like all feats of prestidigitation this requires collusion on the part of the audience.