180 INFECTION AND RESISTANCE 



piece" and the latter globulin sediment as the "mid-piece," assum- 

 ing, on the basis of the conception of Ehrlich, that the globulin frac- 

 tion serves to establish a link between the sensitized cell and the 

 end-piece analogous to that formed by the "amboceptor" between the 

 cell and the whole complement. It is possible, therefore, to treat 

 sensitized cells with mid-piece in such a way that they are thereafter 

 susceptible to hemolysis by the end-piece alone. Such cell-sensitizer- 

 mid-piece combinations have been spoken of by Michaelis as ' f per- 

 sensUized" cells. 



Tsurusaki 53 confirmed the findings of Brand as to the thermo- 

 lability of both "mid-piece" and "end-piece," but was unable to sep- 

 arate the complement of normal hemolysins into the two components 

 in the same way, since he found that hemolytic power was, in such 

 cases, completely destroyed after twenty-four hours of dialysis. It 

 seems to us not impossible that the natural deterioration of alexic 

 power which takes place during such periods of time, at temperatures 

 of from 16 to 20 C., may easily be held accountable for this, since 

 the very feeble sensitization of cells in normal hemolysin complexes 

 requires a correspondingly larger amount of alexin for activation. 



We have mentioned that the so-called "mid-piece" undergoes a 

 rapid change when dissolved in salt solution and, after 3 or 4 hours, 

 may lose its ability to induce hemolysis when added to sensitized 

 cells together with end-piece. Although Hecker 54 was able to con- 

 firm this, he nevertheless showed that this fact does not imply a 

 destruction of the mid-piece. For when such apparently inactive 

 "mid-piece" was added separately to sensitized cells, and end-piece 

 was subsequently allowed to act upon the complex, hemolysis re- 

 sulted. This seems to show that the "mid-piece" undergoes a change 

 on standing in salt solution which does not alter its ability to com- 

 bine with the sensitized cells, but which subjects it to inhibition of 

 such union when end-piece is present. It is also a peculiar fact, evi- 

 dent in many of our own experiments, that when "mid-piece" and 

 "end-piece" are first mixed and then added to sensitized cells the ef- 

 fect in hemolysis is less powerful than when the "mid-piece" is added 

 to the cells first, and the "end-piece" later. This effect is so instan- 

 taneous that, if, in a series of experiments in which combinations of 

 mid- and end-piece are used, the end-piece is run into the tubes con- 

 taining the cells just before the mid-piece is added instead of the 

 other way round, hemolysis is inhibited. 



In working with dialysis, also, w r e have regularly had an experi- 

 ence which may explain the difficulties which many other investiga- 

 tors have had in such experiments. The globulin precipitate, whick 



53 Tsurusaki. Siochem. Zeitschr., Vol. 10, 1908. 



54 Hecker. Arb. a. d. konig. Inst. f. exp. Ther., Frankfurt a/M., Heft 

 3, 1907. See also Guggenheimer. Zeitschr. f. Imm., Vol. 8, 1911. 



