314 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 



CNaCl+KCl 

 whether the quotient ' which 



c Mg Cl 2 +CaCl 2 ' 

 allowed all the animals to swim at the surface, had 

 a constant value. The MgQ 2 +CaCl 2 solution was 

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

 in which they exist in the sea water; namely, n.8 mole- 

 cules MgCl 2 to 1.5 molecules CaQ 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 M Jour. Biol. Ghent., 1915, xxiii., 423. 



