Freshwater ponds are found on a number of islands located in the Seto Inland Sea. The author made observation of the chemical properties of pond water at some of the ponds located on the islands in the western part of the Seto Inland Sea. The primary purpose of this survey was to know the effect of the "sea breeze" from the chlorine contents of pond water. Some of the surveyed ponds were utilized for irrigation. Almost all the surveyed ponds were relatively shallow, and dissolved oxygen was poor in the bottom layer. Chlorine contents were considerably lower than expected. Other chemical compositions and their contents in each pond were not extraordinary; they were of the same order as the average values reported by Dr. S. YOSHIMURA for the lake waters of Japan. The results of the observation and water analysis are shown in Table I.
It seemed that all the surveyed ponds could be utilized for the culture of freshwater fishes.