Studies on hatchability of Schistosoma japonicum eggs in several external environmental conditions.

Several factors influencing the hatching of Schistosorna japonicum eggs were reported by Miyagawa (1916), Faust and Meleney (1924), Magath and Mathieson (1946), Faust (1947), Maldonado and Matienzo (1948), Ingalls et al (1949) and Sugiura et al (1954), but there were only a few investigators who have dealt with the resistance of the eggs to various external environmental conditions. These problems are essential for the elaboration of ffective measures for their control, but many important points in relation to this aspect had been only superficially studied. As to the effect of high and low temperatures, Miyagawa (1916) and Faust (1947) reported very briefly respectively. Several meagre data concerning the effects of salinity and dryness were found in the reports of Miyagawa (1916), Magath and Mathieson (1946) and Ingalls et al (1947). A series of studies designed to provide the resistance of the eggs necessary for a better understanding of the epidemiology of schistosomiasis japonica was thus undertaken. The present paper reported a series of experiments concerning the influence of temperatures ranging from -20•Ž to 60•Ž, salinity, dryness and exprements of host on the hatchability and resistance of schistosome eggs.