The Cosmic Serpent'Cutting edge' GUARDIAN 'Thoroughly enjoyable' SUNDAY TELEGRAPH While living among Peruvian Indians, anthropologist Jeremy Narby became intrigued by their claim that their phenomenal knowledge of plants and biochemistry was communicated to them directly while under the influence of hallucinogens. Despite his initial scepticism, Narby found himself engaged in an increasingly obsessive personal quest. The evidence he collectedon subjects as diverse as