46 DYNAMICS OF LIVING MATTER 



The behavior of Fundulus to distilled water is not the rule for 

 marine animals, as most of them when subjected to it die rapidly. I have 

 recently made a series of experiments with a marine Crustacean Gam- 

 marus, of the Bay of San Francisco.* The osmotic pressure of the 

 sea-water of the bay varies at different times of the year between that 



of about an — and a. % m NaCl solution. When Gammarus is brought 



4 

 suddenly from bay water into distilled water, its respiratory motions 



stop, as a rule, in about half an hour. This standstill becomes per- 

 manent, unless they are put back into sea water within a short time 

 (about ten minutes). If, however, Gammarus be put into a cane 



sugar, dextrose, or lactose solution of any concentration from — to 



8 



I m upward, they die just as rapidly, if not more so, than in distilled 

 water. The same is true when the animals are put into a pure NaCl 

 solution isosmotic with the sea water. They die still more rapidly 

 when put into distilled water, to which all the other salts found in the 

 sea water are added, with the exception of NaCl, and in the concentra- 

 tion in which those salts occur in sea water. If they are put, however, 

 into a solution of NaCl, KCl, and CaCl^, in that proportion in which 

 these salts occur in the sea water, the animals may live as long as forty- 

 eight hours; and if some MgCl^ is added to this solution, the animals 

 may live as long as in sea water. If we prepare solutions composed 

 of only two of the salts contained in the sea water ; namely, NaCl -|- KCl, 

 or NaCl + CaCl^, or NaCl -f MgClj, the Gammarus lives only a few 

 hours. These experiments prove that the medium surrounding the 

 Gammarus must not only have a definite osmotic pressure, but that 

 this pressure must be supplied by specific salts. Perhaps the follow- 

 ing data may explain, in part at least, why this lack of specific salts 

 leads to the death of the animal. 



7. The Antagonistic Effects of Salts 



When the eggs of Fundulus are put immediately after fertilization 

 into a pure solution of NaCl, whose concentration roughly equals that 



in which this salt is contained in the ocean, — , or f m, no egg is 



able to form an embryo. The eggs begin to segment and may go 

 as far as the 64-cell stage, but after this they die. But if to the 

 NaCl solution a small but definite amount of a bivalent metal (with 

 the exception of the most poisonous ones, like Hg), is added, just as 



* Loeb, Imager's Archiv, Vol. 97, p. 394, 1903 ; Vol. loi, p. 340, 1904. 



