THE CULTURE OF VOLVOX AUREUS EHRENBERG

¹ Carolina Biological Supply Company, Elon College, North Carolina

1. Volvox aureus Ehrenberg has been maintained in rich clone cultures for eighteen months without observable decrease in vitality on a medium prepared from spring water, commercial fishmeal, and ferric chloride.

2. The presence of iron in the medium was found to be essential to the continuous culture of Volvox. This was added as ferric chloride. Cultures lacking iron died out in about six weeks.

3. Either local spring water or Huckleberry spring water served satisfactorily in the preparation of fishmeal extract medium, but tap water and distilled water could not be substituted for these.

4. Spring water media containing peptone, beef extract, milk, or urine in various concentrations would not support continuous growth and reproduction of Volvox.

5. Uspenski's medium and modified Knop's solution were found to be of little value in the culture of Volvox.

6. Powdered muscle of the marine butterfish (Poronotus triacanthus Peck) or the fresh-water sunfish (Lepomis gibbosus Linnaeus), with lipoids extracted, could be substituted for commercial fishmeal, while skin and bone could not.

7. Spring water containing only the inorganic salts of fishmeal, or only the proteins, failed to support the culture of V. aureus; but spring water containing the cold water extractives and ferric chloride (one-half cc. of a one per cent solution of FeCl₃·6H₂O/l.) gave excellent cultures which probably could have been carried indefinitely.

8. V. aureus could not be cultured in media containing lactic acid, urea, creatine, uric acid, or a combination of urea, peptone, and lactic acid in the several concentrations used.

9. A readily duplicable method for the culture of V. aureus is described.