FOUR FIGURES
As early as 1878 L. Fredericq demonstrated that the blood and haemolymph of invertebrate marine forms is isotonic with the sea water and it has long been known that Locke's solution and Ringer's solution contain the same proportion of certain salts as does the sea water, only in different concentrations (Loeb, '06). Macallum ('08) has shown that not only does the body fluid of the lower forms of marine life correspond in composition with that of sea water, but also that the plasma of higher animals is not changed in composition from sea water, but is simply more dilute.
Loeb ('06) in his work on the antagonistic action of certain salts, demonstrated the necessity for the presence of the various salts in the composition of sea water, also the importance of the proportion of the various salts one to another in order to obtain normal behavior of certain marine animals.
Although the composition of the sea water varies slightly for different localities, on the whole the salt content remains surprisingly constant, and while an analysis of the sea water for practically any given locality has been determined, it is in general that given by Henze ('10) (taken from Roth) :
Ocean surface To 1000 parts NaCl 26