. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. HALOI'HYLIC ALGA LIMITING FACTORS 217 limis were maintained as previously noted. Under these conditions maximum growth took place between 1 and 2(/c CO», with tz-: 10 hrs. The pH of the growing culture was determined at the same time as the growth rates were measured to see if any change in the pH of the culture occurred and to determine if the change in pi I caused a change in the growth rate. The results of the experiment are plotted in Figure 6. The number of cells/ml is plotted on the left-hand vertical axis and the pH o
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. HALOI'HYLIC ALGA LIMITING FACTORS 217 limis were maintained as previously noted. Under these conditions maximum growth took place between 1 and 2(/c CO», with tz-: 10 hrs. The pH of the growing culture was determined at the same time as the growth rates were measured to see if any change in the pH of the culture occurred and to determine if the change in pi I caused a change in the growth rate. The results of the experiment are plotted in Figure 6. The number of cells/ml is plotted on the left-hand vertical axis and the pH on the right-hand vertical axis, and both are plotted against time. The uninoculated aerated culture medium showed a small pH change (Fig. 6). The culture medium inoculated with X 10" cells/ml increased in pH at the rate of X 10~2 pH units/hr up to 60 hours and a pH of After 60 hours, the pH rose very slowly X 10 :! pH units/hr up to 170 hours and UJ 5 H o CD D O Q 160 140 120 100 80 60 40 20. 0 -I -2 LOG of the K+/Na+RATIO -3 -4 FIGURE 7. The effect of the KYNa+ ratio at (solid triangles) and (solid circles) on the doubling time. Each point represents the mean of at least five determinations. a pH of Figure 6 shows the growth curve and the pH curve plotted against time. One can see that the pH over the range has no effect on the log phase of the growth curve. The same figure shows that the pH is altered rather markedly by the presence of the algae. Figure 7 shows the effect of the K+/Na+ ratio on the doubling time. The opti- mum to occurred between a K+/Na+ ratio of and and decreased at both lower and higher ratios. At the K+/Na+ ratio of the k decreased very rapidly The same phenomenon occurred in both and salt concentrations. DISCUSSION The halophylic green algae are remarkably similar to the marine and freshwater algae in their requirements and growth response, except for their high requirement for an
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