of Carbon Dioxide in Ulva latissima , L. 53 
Section V. Sodium Chloride. 
From the analyses of sea water quoted in the preceding 
section, it will be seen that sodium chloride forms by far the 
largest percentage (2-6-2*7 per cent.) of any of the salts in 
sea water, and this quantity is at least seven times larger 
than the amount of magnesium chloride (0-3 per cent.), the 
next largest constituent. A large number of experiments 
were made in which sodium chloride was alone present in 
the media, and to these reference will first be made. Starch- * 
free Ulva was exposed in solutions of various strengths of 
the purest sodium chloride obtainable, dissolved in either 
distilled water or tap water. In every case, out of about 
thirty cultures with different percentages, a certain amount 
of starch was always found in the cells. Among the first of 
these experiments were those in which the amount of Na Cl 
was the same as in sea water, i. e. 2-65 per cent. The results 
of two of the experiments, one with distilled water and the 
other with tap water as mediums, are as follows : — 
Experiment VI. Feb. 2, 1900. Ulva in 2*65 per cent. 
NaCl in distilled water. 
Date. 
Days. 
Amount of Starch. 
Feb. 5 
3 
moderate 
Feb. 11 
9 
large 
Feb. 20 
18 
large 
Experiment VII. April 15, 1900. Ulva in 2*5 per cent. 
Na Cl in tap water. 
Date. 
Days. 
Amount of Starch. 
Apr. 16 
1 
moderate 
Apr. 18 
3 
large 
Apr. 20 
5 
large 
