The ability of healthy individuals ofPontoscolex corethrurus to survive and maintain its weight in tap water and different concentrations of NaCl and sucrose solution is studied. In water, earthworms survived normally but died at 48 hr exposure in 5% sugar and 0.4% NaCl. In water, an increase of 26% in total body weight was observed at 4 hr exposure. Weight also increased when exposed to 1, 2, 3 and 4% sugar solution, but it decreased in 5% sugar solution. This decrease in weight may be due to osmotic crisis. Similar weight changes have also been observed in NaCl solutions. An increase in weight was observed up to 0.3% NaCl and a decrease in weight in 0.4% NaCl and above.