PHYSICOCHEMICAL PROPERTIES 35 



What makes us hesitate to assume that the precipitant 

 action is the only cause of death, is that we may kill the test 

 animal by relatively small doses of the product and under 

 these conditions, although infarcts are found at autopsy, 

 intravascular precipitates are never found. Furthermore, 

 solutions of luargol in serum or in salt solution added to 

 normal serum retain their clarity longer than in pure dis- 

 tilled water. It seems certain that if the precipitate is not 

 found in serum it is only because of the difficulty of demon- 

 strating it and if serum does not precipitate luargol in vitro, 

 it is because it has lost the salts which play the greatest role 

 in the formation of the precipitate and which are retained 

 by the coagulum, and because albumins prevent precipita- 

 tion of colloids. 



In fact when instead of treating the solution of luargol 

 with serum it is treated with fresh whole blood recently 

 drawn from the carotid and whe'n after violently shaking 

 and centrifuging the mixture, the parts are analyzed sepa- 

 rately, much more luargol is found in the sediment than in 

 the supernant fluid and microscopic examination of the 

 sediment shows finely granular viscous masses. 



To sum up, one may assume with certainty that the rapid 

 death of experimental animals caused by the sudden injec- 

 tion of monosodium preparations is caused only by the pre- 

 cipitate which fills the capillaries and thus produces con- 

 gestion and infarcts in different parts of the organism. The 

 symptoms observed: dyspnea, congestion of the mucous 

 membranes, epileptiform convulsions, gastro-intestinal dis- 

 turbances, fall of blood-pressure, subnormal temperature 

 are identical to those symptoms which are observed in the 

 phenomenon of " anaphylactic shock." The explanation 

 of the mechanism of the reaction and of the crisis which 

 results from it, is, in these cases, easy and simple. We have 

 seen that the arsenobenzenes, soluble in the state of di- or 

 even monosodium salts, are insoluble as neutral bases. 

 The weakest acids replace the sodium of the sodium com- 

 pounds. Consequently when injected into the blood the 

 compound loses its sodium by reason of the carbonic and 

 other organic acids of Ithe plasma, and becomes insoluble. 



