226 STUDIES IN GENERAL PHYSIOLOGY 
contained in the sea-water taken from the ocean in the 
vicinity of Naples is about 3.8 per cent., of which about 3 
per cent. is sodium chloride." 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 
how many grams of NaCl were added to each 100 cc. of 
sea-water. In the first vertical line are indicated the num- 
ber of days that have elapsed since the introduction of the 
Tubularie 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 
N 1 0.6 g. 10¢. 3k. zl " 
Date ea Water NaCl NaCl Nedi Nadi 
Second day.......... 4 1 0) 0 0 
Third day........... 10 2 0) 0 0 
Fourth day.......... 10 8 0) 0 0 
Fifth day............ 12 10 5 1 0) 
Sixth day........... 12 11 5 Ak 0 
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 1.6 g. of sodium chloride 
had been added to each 100 ¢.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 1.6 g. of NaCl is added to 100 ce. of 
sea-water. This value corresponds to a concentration obtained 
by evaporating 100 cc. of sea-water to 69 c.c., if the entire 
1Rora, Allgemeine und Chemische Geologie, Vol. I, p. 524 
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