INORGANIC FOODS. 359 



such closely related chemical elements as sodium and potassium should act 

 so differently physiologically. 



A quite similar observation was made with the Fundvlus heteroclitus. 1 

 This little fish is not at all sensitive to variations in osmotic pressure. 

 It exists in salt water as well as in distilled water, while on the contrary, 

 when placed in a solution of pure sodium chloride of the same concentra- 

 tion as the ocean, it soon dies. Its eggs behave similarly. If to the 

 solution of pure sodium chloride the ions of calcium, barium, strontium, 

 magnesium, lead, cobalt, ferrous iron, zinc, manganese, chromium or alu- 

 minium, are added, the injurious effect of the sodium chloride is combated 

 successfully. On the other hand, the ions of mercury, copper, cadmium, 

 nickel, and ferric iron are without influence. 



The dependence of the cell-function upon the nature of the salts present, 

 and the antagonistic action of different salts, are shown very well by the 

 following experiment: A salt solution of the concentration correspond- 

 ing to sea-water is poisonous to the eggs of the fundulus. Calcium and 

 magnesium exert no recognizable effect upon the eggs. If a fundulus 

 egg be placed in a pure aqueous solution of either of the two last-men- 

 tioned salts, it does not develop. Development takes place, however, 

 immediately on adding a sodium salt to the solution. 



At this place, we will recall the experiments of Martin H. Fischer. 2 By 

 the injection of a J molecular solution of common salt into the veins, he 

 was able to produce a glucosuria which in its entire behavior corresponded 

 to that produced by the diabetic puncture. Such a glucosuria can, in the 

 case of rabbits, be prevented by adding a little calcium chloride to the 

 solution which is injected (975 cubic centimeters of J molecular NaCl solu- 

 tion + 25 cubic centimeters of J molecular CaCb solution). After the 

 elimination of sugar has ceased, it can be renewed by the injection of pure 

 sodium chloride solution, and again checked by means of the calcium 

 chloride solution. 



This reciprocal effect is interesting, and its study opens up new fields of 

 investigation. Each cell has evidently particular salts in specific appor- 

 tionment. A disturbance of this relation by the preponderance of this 

 salt at one time, and that salt at another time, may cause considerable 

 trouble in the economy of the cell. For the present it is necessary for us 

 to study the action of the individual ions separately and in artificial mix- 

 tures. As regards the proportions of the separate ions in the cells, our 

 present methods of investigation can throw no light. It is true that by 

 analyzing the ash, we can get some idea as to the inorganic constituents 

 of an organ. Aside from t'he fact that such an analysis can never give us 



1 Jacques Loeb: Pfliiger's Arch. 80, 229 (1900). Cf. W. A. Osborne: J. Physiol. [Proc. 

 Physiol. Soc. 33, 10 (1905)]. 



2 Pfliiger's Arch. 106, 80 (1904), and 109, 1 (1905). 



