THE NATURE OF TOXIN 113 



The diphtheria fatty acid-colloidal fluids used for injection 

 were not hemolytic for rabbit cells in the test tube, whereas 

 those prepared with the K salts were strongly so. Vesilloff^ 

 showed that the bacilli from very young broth cultures removed 

 by centrifugation and suspended in salt solution were hemolytic. 

 Lubenau^ states that broth cultures are hemolytic between the 

 second and fourteenth days, varying with different strains. 



In seeking an explanation for the instabihty of our artificial 

 toxic colloids we were reminded of the fact that the methods of 

 emulsification so far employed must be of the crudest nature 

 compared with those which accompany the disintegration of the 

 bacilli. We regard the cells, bacterial or other, as consisting of 

 emulsion colloids of water, protein, fat, salts, etc., having at 

 their surfaces or limiting layers an excess of those substances 

 which lower surface tension and aid in regulating permeability, 

 and which, according to the principle of Willard Gibbs must 

 exist at the surfaces, namely emulsified fats, their acids and salts, 

 and protein. The colloidal state of the limiting surfaces is 

 probably different from that within the cells — a reversed type 

 of colloid like a water-in-oil emulsion, in contrast to an oil-in- 

 water emulsion to which one may compare the state of the 

 interior of the cells. ^^ Cells disintegrating or autolyzing in a 

 watery colloidal menstruum such as broth possess dispersion 

 means of remarkable power owing to the highly emulsified state 

 of the fats which, liberated under such conditions, must pass to 

 interfaces in the fluid in a manner far more delicate than we can 

 readily approach in an artificial way. With these ideas in mind 

 we believed we should be able to obtain greater stability in the 

 artificial toxins if we emulsified the fat antigen prior to adding it 

 to the broth. Accordingly we combined the antigen with solu- 

 tions of the commoner proteins at hand such as hemoglobin, 

 casein, egg albumen, gelatin, and a protein derived from the 

 Bad. typhosum, substituting the alkaU salts of the antigen for 

 the fatty acids because of their somewhat greater emulsifying 



8 Russk. Vrach., 1913, October 13, p. 235. 



8 Centr. f. Bakt., 1901, 30, 365. 



" Clowes, Science, 1916, 43, 750-757. 



