ORAN L. RABER 539 



chloride required to produce a solution of the same average conduc- 

 tivity as undiluted sea water, this was the molecular strength decided 

 upon. 



Sea water was concentrated (or diluted) in each case until it pos- 

 sessed the same conductivity as the solution to be tested. After the 

 tissue had been placed in the concentrated (or diluted) sea water 

 long enough to come to equihbrium (20 to 30 minutes) a measurement 

 of the resistance was taken and the material then placed in the salt 

 solution after which the procedure was the same as in the previous 

 experiments. 



Fig. 2 shows the results of these experiments. The results for each 

 concentration of each salt are the average of ten experiments as before, 

 all the concentrations being 0.52 m, with the exception of that of the 

 phosphate. In this case the solubiHty of the disodium salt prohibits 

 a concentration higher than 0.26 m; enough of the monosodium salt 

 was added to produce neutrality and the total molecular concentra- 

 tion reckoned on this basis was about 0.39 m. 



In this series the sulfocyanide takes its place at the top along with 

 the iodide, and at the end of the experiment the two were identical. 

 The nitrate curve is raised a trifle so that it now comes between the 

 bromide and the chloride. The chloride, phosphate, and citrate 

 drop slightly and the tartrate rises slightly, all of which changes are 

 to be expected. 



The greatest changes occur in the sulfate and acetate, which were 

 farthest from 0.52 m in the first set of experiments. The acetate rises 

 and takes its place among the other monovalent salts and the sul- 

 fate drops towards the tartrate and the trivalent salts, thus forming 

 two distinct groups. It should be noted that the acetate comes 

 from Group II up to Group I, but that its rate of fall at the end of 

 the experiment was greater than for the others. 



Several explanations for these phenomena may be given, but it 

 does not seem worth while to enter upon a discussion of them at pres- 

 ent. The recent work of Loeb on the relation between gelatin and 

 electrolytes^ may furnish a clue to the ultimate explanation. 



^Loeb, J., /. Gen. Physiol., 1918-19, i, 39, 237, 363, 483, 559. 



