420 INFECTION AND RESISTANCE 



regarded merely as a giving up from the bacterial cell of preformed 

 endotoxins under the influence of lytic substances which produce 

 greater permeability of the cell membrane was shown by Neufeld 

 and Dold, who extracted bacteria with lecithin salt solution and pure 

 salt solution, and from these extracts (but moderately toxic in them- 

 selves) produced typical anaphylatoxins by the action of complement. 

 The matrix of the poison thus is shown by direct experiment to be a 

 soluble ingredient of the bacterial cell. 



It was further shown by Friedberger and Nathan that the con- 

 ditions prevailing in the test tube experiment in truth represent the 

 processes taking place within the animal body. This they accom- 

 plished by injected bacterial emulsions into the peritoneal cavities of 

 guinea pigs, killing the animals after several hours and examining 

 the peritoneal exudates for their toxic properties. Centrifugalized, 

 cleared of bacteria, and injected intravenously into other guinea 

 pigs, these exudates produced the typical acute symptoms character- 

 istic of the poisons obtained in test-tube experiments. 



It was on these premises, then, that Friedberger 23 was led to 

 formulate his views of the nature of bacterial infections, which give 

 promise of introducing a new understanding of these diseases. It 

 has been shown in the researches upon serum anaphylaxis that the 

 injection of small quantities of a foreign protein may produce reac- 

 tions of temperature which simulate very closely those prevailing 

 in infectious diseases, and variations in the quantities injected, the 

 path of administration, and the interval between injections may lead 

 to conditions, local and systemic, which may affect, more or less 

 profoundly, many different organs and tissues of the body. These 

 matters we have considered in the general discussion of anaphylactic 

 phenomena. Friedberger now suggests that we may regard bacterial 

 infection, after all, as the presence in the body of a living foreign 

 protein in this case varying in distribution and quantity by reason 

 of the particular invasive properties of the given germ and the 

 balance between these and the resistance of the host. It is not neces- 

 sary, therefore, to assume that the character of the disease is deter- 

 mined by the existence of different preformed "endotoxins." He 

 believes that we may justly assume that the toxic substances appear 

 only after proteid cleavage of the bacterial bodies has been initiated 

 Iby the action upon them of the serum components, and that the ap- 

 parent specificity of the poisons, or differences between the toxemic 

 .manifestations of various diseases, may depend, not on differences 

 in the pharmacological actions of these poisons, but rather upon 

 variations in the invasive properties of the bacteria, both as concerns 

 their quantitative distribution and their accumulation and localiza- 

 tion in the infected body. 



23 Friedberger. Loc. cit.; also Deutsche med. Woch., No. 11, 1911 ; Berl. 

 klin. Woch., No. 42, 1911. 



