THE NATURE OF TOXIN 109 



colloidal form, which then, by reason of the necessity for such 

 surface-tension-lowering substances to collect at the interfaces 

 between dispersed and watery phases, become adsorbed upon 

 colloidal particles of a certain size in the broth, forming, with 

 electrolyte, an adsorption entity constituting toxin. We do 

 not believe there is any evidence whatever to show that toxin 

 exists preformed within the bodies of the bacilli and passes 

 through their membranes into the culture medium. The par- 

 ticles of the toxic adsorption aggregate must be very small as 

 we know from the ultrafiltration experiments of Bechhold'' being 

 slightly larger than protalbumoses and smaller than the par- 

 ticles in 1 per cent hemoglobin solution. We reahzed the impos- 

 sibility of reproducing artificially all the changes undergone by 

 medium and bacteria during the life of the culture, but we tried 

 to UTiitate as closely as might be the processes of colloidal nature 

 which we assumed on good evidence to take place. 



The various methods used may be mentioned here: (a) The 

 fatty acid antigen in varying doses, in ether solution, was over- 

 laid on the surface of 100 cc. of broth in Erlenmeyer flasks of 

 250 cc. capacity. This was soon abandoned, (b) The fatty 

 acids were floated in bulk on the broth surface. This method 

 was also unavailable, (c) The fatty acids in alcoholic solution 

 were pipetted upon the surface of the medium, and also emul- 

 sified by mixing at once, (d) The same methods were used 

 with the K and Na salts, and with the ethylic, glyceryl and 

 cholesteryl esters. Several flasks of each description were always 

 made so as to permit of daily examination. All the operations 

 were carried out in a sterile manner. Departures were made 

 from the standard medium to include veal infusion without 

 peptone, peptone solutions alone, and, finally, to eliminate all 

 protein, colloids of mastic-fat in water and salt solution. 



fatty acids, or their salts, derived from the bacteria, in just such amounts as 

 inhibit the growth of the germs, and at the same time cause the lysis of cells. 

 It is significant that the dose of the Na salts of the anthrax antigen just sufficient 

 to prevent the development in broth of the bacilli from spores, 60 mgm. per 

 liter, is that which toxic and lytic broths were found to contain, and approxi- 

 mately that which was added of the alkali salts to the artificial lysins and toxins, 

 as will be shown later. 

 ^ Loc. cit. 



