3i4 The Influence of Environment 



and CaCl 2 , are added the animals will stay permanently 



at the surface and react to light as they would have 



done in normal sea water. These animals also can 



resist comparatively large changes in the concentration 



of the sea water, and it seemed of interest to find out 



t. .1- *u *• CNaCl+KCl 



whether the quotient - , which just 



allowed all the animals to swim at the surface, had 

 a constant value. The MgCl 2 +CaCl 3 solution was 

 3/8 m and contained the two metals in the proportion 

 in which they exist in the sea water; namely, 1 1.8 mole- 

 cules MgCl 2 to 1.5 molecules CaCl 2 . The next table 

 gives the result. 1 Since these experiments lasted a 

 day or more each, usually two different concentrations 

 of NaCl+KCl of the ratio 1:2 or 1:4 were compared 

 in one experiment. 



TABLE XVIII 



1 Loeb, J., Jour. Biol. Chem., 1915, xxiii., 423. 



