ADSORPTION BY SUSPENSIONS OF VARIOUS SUBSTANCES. 223 



the residue from these mixtures proved that erythrocytes adsorb a certain 

 amount of venom. One of the 2 mice injected with the residue from the dog- 

 erythrocyte venom mixture died and the injection of the residue from the 

 stroma-venom mixture caused the death of both of the mice injected. It is 

 possible that a part of the erythrocyte-venom combination had dissolved in the 

 supernatant fluid, and this dissolved substance may have caused the toxicity of 

 the supernatant fluid. We may also have to consider the possibility that some- 

 how dog erythrocytes increase the toxicity of venom. It is, however, quite 

 clear that erythrocytes and stroma adsorb a certain amount of venom. 



Of 9 mice injected with the supernatant fluid from a mixture of guinea-pig 

 brain and dry venom, only that one injected with a quantity corresponding to 

 3f lethal doses survived; 2 injected with a quantity corresponding to 6f lethal 

 doses lived longer than their controls, and the remaining 6 died as soon as the 

 controls. Of five animals injected with the residue from the venom-brain 

 mixture, 4 died. It is difficult to draw a definite conclusion from the results of 

 these experiments, as the supernatant fluid contained particles of brain in sus- 

 pension, which may have adsorbed venom, and their retention in the superna- 

 tant fluid may have increased its toxicity. It was thus necessary to test a fluid 

 entirely free from these particles. We therefore passed the guinea-pig-brain 

 venom mixture through a Berkefeld filter. 



We then carried out a series of experiments comparing the supernatant 

 fluid obtained by centrifugation, the Berkefeld filtrate, and also the Berkefeld 

 filtrate of a guinea-pig-brain venom mixture, which, however, before the fil- 

 tration, had not been shaken for the usual period of 2| hours, but which had 

 been filtered inunediately after mixing. Through this latter experiment we 

 wished to determine whether the passage of the venom-brain through a Berke- 

 feld filter caused either a diminution in the toxicity of the venom through 

 adsorption of venom by the substance of the filter or through clogging of the 

 pores of the filter by minute particles of the brain substance. We found the 

 simple separation of the fluid from the solid portion of the venom-brain mixture 

 by means of the Berkefeld filter did not cause any marked diminution in the 

 toxicity of the filtrate; 4 mice injected with such a filtrate from a venom-guinea- 

 pig-brain mixture died as soon as their controls, and 2 injected with quantities 

 corresponding to 6f lethal doses lived a little longer than the controls. 



All 5 mice injected with the filtrate from the guinea-pig-brain venom mix- 

 ture (after it had been shaken for the usual period of time) lived longer than the 

 controls, but none survived. In the control experiments in which the super- 

 natant fluid from the guinea-pig-brain venom mixture was obtained by centri- 

 fuging, three animals, one injected with a quantity of fluid corresponding to 

 13^ and two with a quantity corresponding to 6f lethal doses, lived longer than 

 their controls, while three other animals died as soon as the controls. We may 

 therefore conclude that guinea-pig brain adsorbs a certain amount of venom, 

 but less than 70 per cent. Here, as in the case of dog erythrocytes and the 

 brain substance of other species, we must consider the possibihty of a toxic 

 combination of venom and brain partly soluble in the supernatant fluid. 



