毒物に対する魚の反応に関する研究-I

Abstract

In previous paper (1), the present author was able to introduce only about the structure of a new gradient tank and the principle of formation of toxic gradient in it. This paper deals with the method of avoidance tests of fishes applying the new tank, in combination with the reactions of Gin-buns, Carassius auratus (L.) and bluegill sunfish, Lepomis macrochirus to acid gradients resulted from adding hydrochloric acid to soft water and hard water. Some data of those tests proved the fact that against pH gradient, Gin-buna were able to approarch fairly acid water with pH as low as 2.8 when the concentration of carbonic acid was lower than 18 p.p.m., whereas bluegill sunfish could approarch only pH 5.8 where the concentration of carbonic acid was 240 p.p.m. Although the pH 2.8 for Gin-buna and the 240 p.p.m. of carbonic acid for bluegill sunfish are presumed to be quickly fatal (4), (9), it is safely to say that those fishes can avoid of fatal concentrations of either hydrogen ion or carbonic acid with a high frequency more than 70 per cent of total avoidance.