60 CLINICAL BACTERIOLOGY. 



Metschnikoff and his pupils, however, obtained opposite 

 results, finding that under the conditions named anthrax- 

 spores thrive and produce virulent cultures. 



Subsequently, the antibacterial activity of the bodily 

 fluids, especially the blood-serum, was studied in the test- 

 tube. The investigations of Fodor, Nuttall, Fliigge, and 

 others demonstrate that the defibrinated blood of various 

 vertebrates destroys anthrax-bacilli in test-tubes, and that 

 this peculiarity of the blood, however, disappears imme- 

 diately on exposure to a temperature of 55 C. (131 F.). 

 The first work of Behring in this domain tended in the same 

 direction. Behring made the discovery that the blood of the 

 white rat destroys anthrax-bacilli, and he made therefrom 

 the deduction that the immunity of the rat to anthrax is 

 attributable to this bactericidal activity. The most thor- 

 ough investigations into these relations emanate from Buch- 

 ner and his pupils. The Munich school assumes that the 

 blood-serum and the bodily fluids derive their bactericidal 

 property from special substances the alexins whose 

 chemic nature has not yet been definitely determined. They 

 are precipitated out of solution by alcohol, are destroyed 

 by exposure for from half an hour to an hour to tempera- 

 tures of from 55 C. (131 F.)to 60 C. (140 F.), and are 

 attenuated by brief exposure to a temperature of 37 C. 

 (98.6 F.), and by prolonged exposure to ordinary. tem- 

 perature. In the absence of salts the alexins are absolutely 

 innocuous. For this reason the serum loses its bactericidal 

 activity when it is dialyzed, or when it is diluted with eight 

 or ten times its volume of distilled water. The original 

 bactericidal activity may, however, be at once restored by 

 the addition of sodium chlorid or other salts. Ammonium 

 sulphate has proved most active in this connection, increas- 

 ing the resistance of the alexins to heat quite ten degrees. 

 The destructive influence of the alexins varies with relation 

 to individual microorganisms. It may be well developed 

 toward one variety of bacteria, and entirely wanting with 

 relation to another. Between these two extremes there are 

 all conceivable gradations. The number of bacteria ex- 

 posed to the .action of the bactericidal serum is, however, 

 always of considerable importance, as even the most active 

 of the^ bodily fluids are incapable of destroying more than a 

 given number of bacteria. 



In spite of these admittedly correct observations, the ex- 



