The Fresh-Water Annelid, Tubifex, as a Pharmacological Test Object

Abstract

A study of the regeneration of the fresh-water annelid, Tubifex, necessitated an evaluation of the factors conducing to its survival in the laboratory. Other workers, have observed its satisfactory survival in tap-water. Our own experience has shown that it will not survive in the tap-water of New Orleans. The significant differences between the tap-water of New Orleans and the compatible tap-water of other cities appear to be the higher concentration of hydroxyl ion (pH 9-10) and the higher concentration of available chlorine of the water of this city. The chlorine content of New Orleans tap-water is stabilized at a minimum of 0.7 ppm by the addition of ammonium salts. To investigate the influence of the reaction of the medium on the survival of Tubifex, solutions buffered with phosphate to cover the range from pH 6 to pH 8.3 were prepared. In the original solutions where the concentration of phosphate ion was 0.03 M there was no survival. The criterion of toxicity was death of all animals at the end of the arbitrarily chosen period of 18 hours. To ascertain at what concentrations of phosphate ion survival would result, a graded series of concentrations of phosphate ion for separate concentrations of hydroxyl ion from pH 4.6 to pH 8.4 were prepared. It was observed that Tubifex does survive in aqueous media if the phosphate ion concentration is low enough and also that the toxicity of phosphate ion is increased if the hydroxyl ion is increased. The toxicity seems to be a conjunctive result of phosphate ion with hydroxyl ion rather than an intrinsic toxicity of hydroxyl ion. This interpretatioll is strengthened by the survival of Tubifex in aqueous media from which phosphate ion was excluded in the range pH 5.0 to 9.5.