The Culture and Division Rate of Stentor coeruleus.

Abstract

Due to the difficulty of carrying on isolation cultures of Stentor coeruleus, 1 this protozoan has not been much used in pedigreed culture work. Hetherington 2 has recently published a culture method for this organism. He did not, however, continue the culture of Stentor for longer than 7-day periods, and also found some difficulty in keeping Stentor alive, using different types of Protozoa as food, and various media as the basis of his cultures. Beers 3 4 has shown that Didinium can be cultured at a constant division rate if fed on a superabundant diet of Paramecium. At the suggestion and with the advice of Dr. J. A. Dawson, the writer began experiments to determine a suitable method of culturing Stentor coeruleus using Blepharisma undulans as the source of food.

A pure line of Stentor coeruleus was begun by isolating a single individual. As a result of 2 successive divisions four individuals were isolated and used to begin a pedigree culture of 4 lines. Each individual was placed in a separate culture dish containing 1.0 cc. of spring water (changed on June 18, 1936, to 0.8 cc) of pH 7.2. The food consisted of a constant number of washed Blepharisma undulans (100–110 individuals per cc. of spring water). Isolations to fresh medium were made every 24 hours. The temperature at which the experiment was carried out was 22.1° ± .08°C. The minimum temperature during the course of the experiment was 20.1°C. and the maximum, 25.8°C.

The graph (Fig. 1) shows conclusively that the medium used is conducive to good growth of Stentor coeruleus, inasmuch as during the entire period the average fission rate fell below 0.5 divisions every 24 hours only 3 times, and, for the few months during which the experiment was carried on, the average rate was 6.5, with only minor fluctuations above and below.