Effects of Calcium and Citrate Ions. 5 



until the solution containing no calcium and 100 per cent, citrate 

 gave no precipitation. It will thus be seen that when approxi- 

 mately two equivalents of citrate were mixed with one of calcium 

 no precipitation of the oleate solution occurred. The toxic effect 

 of the same series of solutions when injected intravenously in mice 

 showed a similar curve, the maximum dose of either the 100 per 

 cent, calcium or the 100 per cent, citrate which could be adminis- 

 tered to a mouse weighing 20 grammes being .25 c.c. As the point 

 was approached at which no precipitation of oleate occurred, 

 doses ranging from 2 c.c. to 4 c.c. could be injected intravenously, 

 and at a critical point representing approximately 35 per cent, 

 calcium it was not found possible to exert any appreciable effect 

 upon the animals even by doubling the concentrations of the 

 solutions employed. The effect exerted by the same mixtures of 

 calcium and citrate upon the process of hemolysis of blood cor- 

 puscles by means of complement and amboceptor exhibited a 

 similar curve. The solutions containing 1 00 per cent, calcium 

 with no citrate and 100 per cent, citrate with no calcium entirely 

 prevented hemolysis in the presence of an amount of amboceptor 

 and complement four times that required to produce hemolysis 

 in a normal system. With the decreasing proportion of calcium 

 in the first case and citrate in the second, hemolysis took place 

 more rapidly and at a critical point lying between 35 per cent, 

 and 38 per cent, of calcium the interference with hemolysis was 

 practically negligible. It will be seen, therefore, that the point 

 at which oleate is not precipitated from its suspension in water 

 corresponds almost exactly with that at which no disturbing effect 

 is exerted on mice, or the process of hemolysis. At this critical 

 point calcium and citrate are present in a ratio of approximately 

 one chemical equivalent of calcium to two of citrate or three 

 molecules of calcium chloride to four of trisodium citrate. This 

 close coincidence lends support to the view that positive ions exert 

 their protective effect in biological systems by counteracting the 

 destructive effect of negative ions on a continuous or external 

 lipoid phase of protoplasm in a manner similar to that outlined 

 in a subsequent paper dealing with anesthetics. 



