THE Geographical Journal for December contains an interesting monograph, by Dr. Wistenra Sambon, upon the acclimatisation of Europeans in tropical lands. The subject-matter of this paper was discussed at the Royal Geographical Society last April, and various opinions were expressed upon it. Dr. Sambon is, further, the author of other communications dealing with this question. Put briefly, his contention is that there is nothing inimical to Europeans in tropical climates which cannot be prevented by hygienic measures. The two main characteristics of the tropical climate, viz. heat and moisture, are practically never per se the cause of disease, nor do they per se cause any deterioration in either the colonists themselves or their progeny. The mass of the so-called diseases of tropical climates has a parasitic origin. The enormous number of deaths from malaria in the unhealthy regions of Africa, and from snake-bite in India, are quoted by the author as examples of this. Even heat-stroke is, according to him, of parasitic origin. Further, not only is the great enemy to colonisation after actual occupation, the microbe, but the same agency comprises the great difficulty in colonisation. For instance, in the French Expedition to Madagascar in 1896, only seven men were killed by Hovas, and ninety-four wounded; the deaths due to pathogenic micro-organisms numbered 6000, and the sick list from the same cause 15,000. From these facts the contention is that all we have to do in order to make Europeans thrive in the tropics, is to exterminate the pathogenic micro-organisms which are the cause of so-called tropical disease; these once subjugated, and Europeans could live in the tropics like natives.