220 



STUDIES IN GENERAL PHYSIOLOGY 



contained in the sea-water taken from the ocean in the 

 vicinity of Naples is about 3.S p ( -r cent., of which about 3 

 per cent, is sodium chloride. 1 The following table shows 

 how with an increase in the amount of NaCl regeneration is 

 inhibited more and more, and finally prevented altogether. 

 The figures in the first horizontal line of the table indicate 



O 



how many grams of NaCl were added to each 100 c.c. of 

 sea- water. In the first vertical line are indicated the num- 

 ber of days that have elapsed since the introduction of the 

 Tubulariio into the solutions. In the horizontal lines after 

 each date are given the number of polyps regenerated up to 

 that date. The stems were all taken from the same colony, 

 and each solution contained twelve stems. 



TABLE I 



In order not to make the table too long, I will add that 

 no regeneration whatsoever occurred in the most concentrated 

 of these solutions that in which 1.0 g. of sodium chloride 

 had been added to each 100 c.c. of sea-water. The retardation 

 of regeneration was well marked, even when only 1 per cent. 

 NaCl was added to the sea-water, and even in such a solu- 

 tion not all the animals regenerated. The repetition of these 

 experiments yielded the same results. 



The concentration in which no regeneration occurs is 

 therefore reached when 1.0 g. of NaCl is added to 100 c.c. of 

 sea-water. This value corresponds to a concentration obtained 

 by evaporating 100 c.c. of sea-water to 09 c.c., if the entire 



1 ROTH, Allgemeine und Chemische Geologic, Vol. I, p. 524. 



