386 



GRACE MEDES 



when alkalinity is most essential for growth. The increased 

 growth might be accounted for by the fact that in the solutions 

 in which sea-water is diluted with iso-tonic NaCl, a reduction 

 of the salts of Mg and Ca, two elements antagonistic to Na, 

 occurs, and the stimulating effect of the Na might be expressed 

 in the increased size. This is the most striking modification 

 produced by the NaCl solutions. 



Figs. 99 to 102 Experiment 14. NaCl, 0.52M. 



Fig. 99 14a, 72 hrs. Control. 



Fig. 100 14c, figure 101 lie, figure 102 14/. 72 hrs. Characterized by reduced 

 body-size and proportionately longer arms. The processes while not reduced in 

 number are longer and more thorn-like. The lattice-work in the arms is more 

 open, although the connecting branches are about as numerous as in the normal. 



Another effect of increased NaCl content is the decreased 

 length of the body-rods. Figures 99 to 102 illustrate all these 

 modifications. Figure 99 represents the control at 72 hours; 

 figure 100, one from culture c; figure 101, from e and 102 from/. 

 In the solutions of gradually increased NaCl content, we may 

 observe the longer and more spiked character of the typical proc- 



