ENDOTOXINS 121 



Method of Obtaining Endotoxic Substances. Endotoxic substances 

 are obtained from bacteria by thorough disintegration of the bodies. 

 This is accomplished by various methods: (a) The substances may be 

 found in old cultures as a result of death and disintegration of numbers 

 of bacteria; (6) they may be obtained by suspending the microorganisms 

 in distilled water and shaking in a machine, much as Wassermann and 

 Citron's artificial "aggressins" are prepared; (c) the bacteria may be 

 dried and ground to a fine powder, as in the preparation of Koch's 

 "bacillen emulsion" of tubercle bacilli; (d) MacFadyen freezes masses of 

 bacteria with liquid air, and then grinds them into a fine powder; (e) 

 Conradi recommends autolyzing the bacterial cells in non-nutrient 

 fluids; (/) Rosenau has studied the endotoxins of pneumococci obtained 

 by alternate freezing and thawing of suspensions in distilled water; (g) 

 Vaughan has devised a method of growing massive cultures on solid 

 media several square yards in extent, removing the bacteria with sterile 

 salt solution, and digesting the bacterial masses with an excess of a 2 

 per cent, solution of caustic alkali in absolute alcohol. 



In the body, the endotoxins are probably liberated either by autolysis 

 or by disintegration through the bacteriolysins, complements, or enzymes 

 of the body-cells and fluids. 



Nature of Endotoxins. Owing to their insoluble nature, endotoxins 

 in pure form and free from other products of bacterial activity, cannot 

 be obtained. As a result, their chemical nature and structure are un- 

 known. Tuberculin, which was formerly believed to be an albumose, 

 may be produced in a protein-free medium ; it seems probable that this 

 substance is of the nature of a polypeptid, giving no biuret reaction, but 

 being destroyed by pepsin and trypsin (Laevenstein and Pick 1 ). Whether 

 or not tuberculin is an endotoxin liberated upon the disintegration of the 

 bacilli is unknown. Pick regards it as a secretory product closely 

 related to the true toxins. It is probable that some toxin is actually 

 secreted into the culture-medium, and that the major portion, which is 

 of a somewhat different nature, is intimately related to the constituents 

 of the bacterial cells. 



There is little doubt but that endotoxic substances are highly poison- 

 ous, and that they are chiefly responsible for the characteristic symptoms 

 of diseases produced by the bacteria that contain them. Whether, 

 however, they are actually preformed definite and specific constituents 

 of bacteria, or merely the poisonous products of disintegration of the 

 bacterial proteins, is still undecided. It would appear that bacteria 

 1 Biochem. Zeit., 1911, 31, 142. 



