114 C. C. WARDEN, J. T. CONNELL AND L. E. HOLLY 



properties. The colloids formed in this manner were of great 

 interest. If to a solution of 10 mgm. of hemoglobin in 5 cc. of 

 salt solution there was added drop by drop the alcoholic antigen 

 solution a somewhat opalescent colloid resulted. When this 

 mixture was added to the standard broth in constant motion 

 drop by drop there resulted beautifully clear, stable liquids even 

 when the amount of fat antigen exceeded 200 mgm. per 1 liter. 

 When, however, the hemoglobin solution alone, or the hemo- 

 globin-antigen solution was added to the broth all at once, 

 instead of gradually, the resulting fluids became cloudy. The 

 same results were noted" with fat-free casein-antigen and the 

 typhoid protein-antigen mixtures. The emulsions made with 

 fresh egg white and with gelatin were never perfectly clear. 



Of particular interest were the colloids made with the typhoid 

 protein-antigen emulsions. The typhoid protein itself, of which 

 mention has been made m an earlier paper, is soluble in salt 

 solution, non coagulable by heat, contains but traces of amino 

 nitrogen and is highly toxic for laboratory animals in small 

 doses. It is toxic also when its solution is mixed with broth 

 by the drop method, 1 cc. of the fluid containing 0.25 mgm. 

 injected intraperitoneally into guinea-pigs being fatal in twenty- 

 four hom's. On the other hand twice the dose produces no symp- 

 toms at all if the protein solution be added to the broth all at 

 one time. The addition of the fat antigen to the colloid increases 

 the toxicity, and gives to the autopsy picture its distinctive 

 character. Guinea-pigs dying from the effects of the protein 

 alone present no signs beyond sUght injection of the visceral and 

 parietal peritoneum whereas those dying from the protein 

 antigen emulsions show characteristic signs of diphtheria toxin 

 poisoning. We do not believe that the ,typhoid protein, derived 

 as it is from the germ bodies that have undergone prolonged 

 defatting extractions with alcohol and with ether, represents 

 the proper protein of the bacteria during life, but this view does 

 not militate against the conception that the proteins of som.e 

 microorganisms liberated by autolysis in fluids may also be 

 somewhat toxic if emulsion in a proper colloidal state occurs. 

 We are inclined to the belief that the potentialities for toxin 



