196 INFECTION AND RESISTANCE 



tion is usually sufficiently marked to render the use of whole bacteria 

 unreliable for specific fixation experiments. For this reason, as we 

 will see, bacterial extracts must be used in such work unless careful 

 quantitative controls are made. Upon what this fixation depends it 

 is difficult to determine. It may be that it is purely non-specific and 

 due to absorption of the fine emulsion of the bacteria comparable to 

 that observed on the part of kaolin or quartz sand emulsions, or, pos- 

 sibly fixation by such bacterial emulsions may occur because of the 

 small amounts of normal sensitizer almost always present in the 

 serum employed as alexin. 



Apart from the lipoids, a number of other substances have been 

 found to fix alexin and exert consequent antihemolytic action. Thus 

 Landsteiner and Stankovic, 103 and Landsteiner and von Eisler 104 

 describe the anti-alexic action of various proteins coagulated or pre- 

 cipitated. They refer this action not to particular chemical struc- 

 ture but to the colloidal state, since they obtained similar antilytic 

 action with such inorganic emulsions as quartz sand and kaolin 

 (aluminium-orthosilicate). Since anticomplementary action has, 

 moreover, been noted in the case of a large number of extracts of 

 such materials as wool, leather, etc., it is clear that the methods of 

 alexin fixation, as applied to the forensic differentiation of blood, 

 must be carefully controlled with this point in view. 105 



Among the most practically important non-specific agencies 

 which fix alexin there are some which appear under certain condi- 

 tions in normal serum. Noguchi 106 has found that serum will often 

 develop anticomplementary properties as a consequence of heating 

 during the process of inactivation. On more detailed investigation 

 he determined that the anticomplementary action increased as the 

 serum was heated to about 90 C. Above this temperature it is de- 

 stroyed. He refers this property to the serum lipoids, since he was 

 able to remove it by extraction with ether, the ether extract possessing 

 the same anticomplementary power as the original serum. 



Neisser and Doring 1 7 have noticed anti-alexic or anticomple- 

 mentary properties of human sera which were destroyed on heating, 

 and which they associate with disease of the kidneys, since they 

 noted it in sera of uremic patients. Browning and McKenzie 1( 

 have observed a similar heat-sensitive anti-alexic action on the part 

 of normal serum, and the subject has been studied by Zinsser and 

 Johnston. 109 It was found that all normal sera will develop anti- 



103 Landsteiner and Stankovic. Centralbl f. Bakt., 1906, Vols. 41 and 42. 



104 Landsteiner and von Eisler. Wien. kl. Woch., 1904, No. 24. 



105 Uhlenhuth. Deut. med. Woch., 1906, Nos. 31 and 51, and Centralbl. f. 

 Bakt., 1906, I, Ref., Vol. 38. 



106 Noguchi. Journ. of Exp. Med., Vol. 8, 1906, p. 726. 



107 Neisser and Doring Berl. kl. Woch., 1901, No. 22. 



108 Browning and McKenzie. Journ. of Path, and Bact., Vol. 13, 1909. 



109 Zinsser and Johnston. Journ. of Exp. Med., Vol. 13, 1911. 



