Edward Hamilton Aitken, the author of the following sketches, was well known to the present generation of Anglo-Indians, by his pen-name of Eha, as an accurate and amusing writer on natural history subjects. Those who were privileged to know him intimately, as the writer of this sketch did, knew him as a Christian gentleman of singular simplicity and modesty and great charm of manner. He was always ready to help a fellow-worker in science or philanthropy if it were possible for him to do so. Thus, indeed, began the friendship between us. For when plague first invaded India in 1896, the writer was one of those sent to Bombay to work at the problem of its causation from the scientific side, thereby becoming interested in the life history of rats, which were shown to be intimately connected with the spread of this dire disease. Having for years admired Eha's books on natural history—The Tribes on my Frontier, An Indian Naturalist's Foreign Policy, and The Naturalist on the Prowl, I ventured to write to him on the subject of rats and their habits, and asked him whether he could not throw some light on the problem of plague and its spread, from the naturalist's point of view.