DR. WATSON'S book shows clearly the wide range of scientific knowledge which is required by those who work in the tropics either as physicians or as sanitarians. It is unnecessary nowadays to insist upon the importance of the control of malaria in the development of those vast areas from which is derived so much of the food supplies and raw materials of manufacture of all civilised countries, but only those who have had practical experience of the methods used to deal with the disease can appreciate how many and how varied these must be.