This monograph deals with curious and little-known acoustic systems of commun ication based on whistling that are in use at the present time in many parts of the world and have had, on the evidence available, even greater currency in the past. In spite of their wide distribution, they have not so far received the attention they might have been expected to attract: linguistically and in other ways they are most interesting. For it should be realized that they are much more than mere codes or conventional systems of signals; they function in exactly the same way as speech (in the sense we...