Respiratory Exchange of the Fresh Water Annelid,Tubifex

Abstract

During an investigation to determine the availability of Tubifex tubifex as a test-object for certain pharmacological studies it was desired to define the magnitude of its respiratory exchange.

The method of Warburg 1 for measuring oxygen utilization (Qo_o2) and that of Dickens and Simer 2 for determining the respiratory quotient (R.Q.) were used. An aqueous medium containing NaCl— 0.32%, KC1—0.007%, CaCl₂—0.00074%, and NaHCO₃ —0.005%, possessing a pH range from 7.0 to 7.1, was used in the experiments. An atmosphere of oxygen; since it was found to be as suitable as air, was used for the sake of expediency in calculations. The most suitable temperature for these experiments was found to be 30°C; a few determinations were made at 25°C.

In most experiments preliminary anesthesia with chloretone (0.2%) was used to free the animals from mud and to sort them. Anesthesia lasting no more than 10 minutes was induced well in advance of the experiment. The data obtained from several comparative experiments indicate that such anesthesia induced long before the experiment did not modify appreciably the nature of the respiratory exchange.

The animals were arbitrarily divided into two categories based on length: small—about 2 cm; large—about 7 cm. No attempt to segregate the animals on a basis of sexual phase was made.

Utilisation of Oxygen: In 12 determinations the average utilization of oxygen (Qo₂) by small worms at 30°C was 1.49 cmm O₂ per mg dry weight per hour when the animals were previously fasted for 16 hours. The average Qo₂ (4 determinations) for small worms previously fed glucose for 16 hours was 2.19. The experimental medium for the latter contained 0.2% glucose.

The addition of glucose to the experimental medium had little effect on the Qo₂ of small worms previously fasted 16 hours.