342 ROBERT AARON STEINBERG 
14. The effect of increasing the concentration of the magnesium sulphate in the Pfeffer 
solution. 
MgS04.7H20 (Kahlbaum). 
Strain W, i 
Strain Y, i 
Control 
o.oi Mg. Zn/L 
Control 
0.01 Mg. Zn/L 
0.302 g. 
0.602 g. 
0.516 g. 
0.806 g. 
0.265 
0.578 
0.535 
0.830 
0.339 
0.562 
0.546 
0.843 
0.330 
0.528 
0.409 
0.694 
0.335 
0.554 
0.393 
0.732 
0.317 
0.565 
0.480 
0.781 
Strain W, i 
10 : 5 : 22.5 
10 : 5 : 42.5 
10 :5 :62.5 
10 : 5 : 82.5 
10 : 5 : 102.5 
0.530 g. 
0.586 g. 
0.669 g. 
0.621 g. 
0.810 g. 
0.372 
0.448 
0.638 
0.730 
0.907 
0.451 
0.517 
0.654 
0.676 
0.859 
Strain Y, i 
10 : 5 : 22.5 
10 : 5 :42.s 
10 : 5 : 62.5 
10 : 5 : 82.5 
10 : 5 : 102.5 
0.600 g. 
0.663 g. 
0.817 g. 
0.746 g. 
0.980 g. 
0.487 
0.600 
0.757 
0.775 
I.OI7 
0.544 
0.632 
0.787 
0.761 
0.999 
Retardation of spore formation only in 10 : 5 : 102.5 (NH4NO3 : KH2PO4 : MgS04. 
7H2O). With increased concentrations of MgS04.7H20 the spores became more and more 
brown colored. 
15. The effect of increasing the concentration of the magnesium sulphate in the Pfeffer 
solution. 
Strain W, 2 
10:5 :2.5 
10 :5 : 77.5 
10 : 5 : 83.75 
10 : 5 : 90 
10 : 5 : 96.25 
0.224 g. 
0.613 g. 
0.646 g. 
0.695 g. 
0.735 g. 
0.248 
0.625 
0.674 
0.745 
0.800 
0.236 
0.619 
0.660 
0.720 
0.768 
10 : 5 : 102.5 
10 : 5 : 108.75 
10 : 5 : 115. 0 
10 : 5 : 121.25 
10 : 5 : 127.5 
0.722 g. 
0.832 g. 
0.865 g. 
0.818 g. 
0.929 g. 
0.747 
0.778 
0.802 
0.834 
0.930 
0.735 
0.810 
0.834 
0.824 
0.930 
Strain Y, 2 
10 :5 :2.5 
10:5 :77-5 
10 : 5 : 83.75 
10 : 5 : 90.0 
10 :5 : 96.25 
* 0.720 g. 
0.661 g. 
0.647 g. 
0.743 g. 
0.658 g. 
O.5II 
0.720 
0.750 
0.692 
0.804 
0.51 1 
0.691 
0.699 
0.718 
0.731 
* Accidental zinc culture. 
