412 RELATIVE TOXICITY OF HALIDES 



According to Biedermann (1921), animal and vegetable diastases 

 consist of a thermostable, organic component, by itself inactive, 

 and a thermostable coenzyme. Numerous inorganic salts can act 

 as the coenzyme, mainly through the action of their anions. The 

 sodium salts in order of greatest effect are the chloride, bromide, 

 nitrate, iodide, and sulphate. 



The bromide ion distributes itself between blood corpuscles and 

 plasma in a ratio (1:3.1) similar to that for the corresponding dis- 

 tribution of chloride ions (1 :2.1) (Wiechmann, 1921). 



It is evident that bromides and iodides can to a certain extent 

 replace chloride in the circulating and tissue fluids and secretions of 

 the body with apparently the same functional effect, and without 

 producing definite toxic symptoms. This research, carried out dur- 

 ing the winters of 1919-20 and 1920-21, is directed toward the solu- 

 tion of the problem of to what extent such non-toxic replacement 

 can take place. 



In view of the fact that the iodine of sea water is present chiefly 

 as iodate (Sonstadt, 1872, and Winkler, 1916) a comparative study 

 of iodate has been included. 



As a basis of comparison we have measured the survival times 

 of frog heart and muscle-nerve preparations immersed in modified 

 Locke solutions containing mixtures of the ions studied. 



While much work has been carried out in determining the relative 

 eft'ects of various series of cations on the skeletal and cardiac muscles 

 of the frog, less has been done with series of anions. 



Loeb (1909) has shown that the relative effectiveness of halide 

 ions in producing rhythmic contractions (a toxic effect) in muscle 

 is given by the order, F > I > Br > CI, the minimal concentrations 

 being for NaF, m/64 to m/96; for Nal, m/32; for NaBr, m/16 to 

 m/32; and for NaCl, m/16. This is connected, as Loeb points out, 

 with the rapidity of passage into the muscle. He has recently shown 

 (1919-20) that the same order holds for the influence of these ions on 

 the rate of diffusion of water through collodion membranes. 



Kruse (1919) has shown that a bromide-Ringer or Locke solution 

 is inadequate to maintain rhythmicity in a perfused isolated mam- 

 malian heart for as long a time as a similar chloride solution, but claims 

 that in the frog heart the bromide-Ringer solution is at least as effi- 



