176 INFECTION AND RESISTANCE 



blood cells were thoroughly washed free of serum soaps did not have 

 this hemolyzing action, and Friedemann and Sachs 37 claimed that 

 they were unable in any case to inactivate the hemolytic serum soap 

 mixtures by heating to 56 C. These writers, as well as others, 

 attribute Noguchi's results to the fact that the sera which he used to 

 produce his "artificial complement," i. e., his serum soap mixtures, 

 were heated to 50-51 C. only, a fact which would justify doubt of 

 complete inactivation. Knaffl-Lenz 38 has more recently carried out 

 experiments on the same question. His results seem to show that the 

 hemolytic action exerted by fatty acids or soaps is a phenomenon 

 quite incomparable to true complement action, and that these hemoly- 

 sins are heat stable, remaining unchanged by heating at 56 C. We 

 have referred in a number of places to the analogy between alexins 

 and ferments or enzymes. The chief objection to this conception 

 formerly brought forward was based upon the fact that the comple- 

 ment or alexin, unlike an enzyme, was used up during its reactions, 

 and that a definite quantitative relationship existed between the 

 alexin and the amount of cells or bacteria upon which it could act. 

 Recent experiments by Kiss 39 seem to show that this quantitative re- 

 lationship is not as strict and regular as was formerly supposed. He 

 showed that the action of complement depends very largely upon its 

 concentration. For instance, to cite his work directly: "0.05 com- 

 plement is sufficient to hemolyze completely a definite quantity of 

 sensitized blood cells if the experiment is done in a total volume of 

 5 c. c. 0.02 c. c. of complement gives absolutely no hemolysis in a 

 similar volume. When, however, the total volume is reduced to 2.5 

 c. c., then 0.02 c. c. of the complement begins to act, and it produces 

 complete hemolysis if the total volume is reduced to 1.25." In fur- 

 ther developing this observation he showed that, if sufficiently con- 

 centrated, a very small amount of complement can act upon an ex- 

 tremely large amount of red blood cells, an amount incomparably 

 larger than those acted upon in more dilute solutions. These observa- 

 tions would tend to strengthen considerably the conception of the fer- 

 ment nature of alexins in general. 



Kiss' observations are furthermore in agreement with the inves- 

 tigations of Liefmann and Cohn, 40 whose work we have mentioned 

 in the preceding chapter on Cytolysis. These writers assert that the 

 fixation of complement during hemolysis is not due to its chemical 

 union with the sensitized cells, but is due to fixation by the end 

 products of the reaction ; in other words, by the stromata of the red 

 cells and possibly by other substances given up by these cells. A 

 further factor contributing to the disappearance of complement in 



37 Friedemann and Sachs. Biochem. Zeitschr., Vol. 12, 1908. 



38 Knaffl-Lenz. Biochem. Zeitschr., Vol. 20, 1909. 



39 Kiss. Zeitschr. f. Imm., Vol. 3, 1909. 



40 Liefmann and Cohn. Zeitschr. f. Imm., Vol. 8, 1911. 



