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. In response to this appeal he wrote a most informing and characteristic article for _The Times of India_ (July 19, 1899), which threw a flood of light on the subject of the habits and characteristics of the Indian rat as found in town and country. He was the first to show that _Mus rattus_, the old English black rat, which is the common house rat of India outside the large seaports, has become, through centuries of contact with the Indian people, a domestic animal like the cat in Britain. When one realises the fact that this same rat is responsible for the spread of plague in India, and that every house is full of them, the value of this naturalist's observation is plain. Thus began an intimacy which lasted till Eha's death in 1909. The first time I met Mr. Aitken was at a meeting of the Free Church of Scotland Literary Society in 1899, when he read a paper on the early experiences, of the English in Bombay. The minute he entered the room I recognised him from the caricatures of himself in the _Tribes_. The long, thin, erect, bearded man was unmistakable, with a typically Scots face lit up with the humorous twinkle one came to know so well. Many a time in after-years has that look been seen as he discoursed, as only he could, on the ways of man and beast, bird or insect, as one tramped with him through the jungles on the hills around Bombay during week-ends spent with him at Vehar or elsewhere. He was an ideal companion on such occasions, always at his best when acting the part of _The Naturalist on the Prowl._