THE EFFECTS OF VANADIUM, COPPER, MANGANESE AND IRON ON THE SYNTHESIS OF PROTOPLASM BY CHILOMONAS PARAMECIUM

¹ From the Zoölogical Laboratory, The Johns Hopkins University, Baltimore, Maryland

1. Experiments were performed to ascertain the effect of vanadium (VOCl₂ and Na₃VO₄), copper (CuCl₂), manganese (MnCl₂) and iron (FeCl₃) in acetate-ammonium solution on the rate of reproduction and the synthesis of starch and fat in Chilomonas paramecium.

2. Tetravalent vanadium in VOCl₂ causes marked increases in the frequency of division in Chilomonas which vary with the concentration. As the concentration of VOCl₂ added to the acetate-ammonium solution was increased, the frequency of division increased to a maximum at approximately 10^-5 M and then decreased. Pentavalent vanadium in Na₃VO₄ causes no increase in frequency of division. Tetravalent vanadium at certain concentrations is therefore beneficial for growth of Chilomonas and pentavalent vanadium is not.

3. Neither copper, manganese nor iron in acetate-ammonium solution causes any statistically significant increase in the frequency of division of Chilomonas, and neither manganese nor iron causes a significant decrease in the frequency of division, but as the concentration of copper increases from 10^-12 M the frequency of division decreases, ceasing entirely at 3 x 10^-7 M.

4. Chilomonas has been grown continuously for eight years in acetate-ammonium solution with no additions of copper, manganese or iron. This shows conclusively that if the metals are needed extremely minute quantities suffice, but it does not prove that they are unnecessary for there are doubtlessly traces of them in the solution.

5. The starch and fat content of Chilomonas varied from no starch and much fat to much starch and little fat in all the solutions used; therefore, this variation was not caused by the addition of either vanadium, copper, manganese or iron. It was found in all solutions to be correlated with the rate of reproduction.