390 



GRACE MEDES 



Experiment 17. Plot 16. July U, 1915 



Plot 16 



The control developed rather slowly at first, but ultimately 

 reached a size slightly greater than that of the general average. 

 In the experimental solutions, decrease of size was very slight 

 and the various cultures maintained very nearly the same pro- 

 portions throughout. In e, 40 cc. 0.60M NaCl to 60 cc. sea- 

 water, the solution of greatest NaCl percentage in which the 

 specimens survived 120 hours, the average size was 80.6 per 

 cent of that of the control. Except h, all the cultures in which 

 the specimens formed skeletons lived the same length of time 

 as did those in the previous experiment. 



In the experiments in which the solutions of NaCl employed 

 were of higher concentrations, an important variation in the 

 medium was produced, — an increase of osmotic pressure. In 

 solution 156, the physical effect of the hypertonic solution was 

 about sufficient to neutralize the physiological effect of the 

 sodium, but in solutions of increased density, such as, 15c, 

 166, 176, etcetera, the inhibiting effect of the hypertonic solu- 

 tion outweighed the stimulating effect of the sodium. 



