It may be safely stated that anything which Dr A. C. Houston writes on the subject of water bacteriology is received with very great interest and respect, and his recent report on the bacteriological characters of Bacillus coli in raw, stored and filtered river water (Metropolitan Water Board, 7th Report on Research Work) is no exception to the rule. The report is of very great interest to all engaged in the study of water bacteriology, particularly in England. We who are working on this subject in a tropical country have different conditions around us, and we naturally look at things from a somewhat different standpoint, so that a brief description of our experience, and a criticism of Dr Houston's results in the light of our ideas will probably be of interest to many who are engaged in this fascinating subject.