CYTOLYSINS 133 



should be possible to break up a complement so as to demonstrate a 

 haptophore group and a zymophore or zymotoxic group. Thus, ex- 

 posure to increased temperature might be so arranged as to destroy 

 the zymophore group and leave the haptophore group intact. If this 

 were true, the haptophore group or complementoid might be added to 

 an antigen-amboceptor mixture and thus prevent any further action 

 by a fresh whole complement. Experimentally, however, it was found 

 that this, in the majority of instances, does' not occur. Nevertheless, 

 Ehrlich and Sachs found that if they mixed inactivated guinea-pig 

 serum, normal inactivated dog serum, and guinea-pig cells, hemolysis 

 did not occur, even after the addition of fresh guinea-pig serum. They 

 believed this to be the result of a blocking or plugging of the com- 

 plementophile group of the dog amboceptor by the complementoid of 

 the inactivated guinea-pig serum, thereby preventing the union when 

 fresh active complement was added. Fuhrmann supported this state- 

 ment and maintained that allowing the complement to stand for a 

 period of three weeks was even more adapted to separation of the hapto- 

 phore and zymophore group. Following this work, Muir and Brown- 

 ing conducted an extensive series of complicated experiments, which 

 in the main tend to support the view of Ehrlich that complementoids 

 actually exist. If they do exist, however, they are not uniformly demon- 

 strable, and it may very well be that this is due to the difference in 

 destructibility of the two groups being so slight that our methods of 

 differentiating by means of heat and standing are not sufficiently exact. 

 Complement Fractions. Further light was thrown on the possi- 

 bility of fractioning complement by the experiments of Ferrata, who 

 found that dialyzation of the serum resulted in the destruction of com- 

 plementary activity. Dialyzation precipitates the so-called globulin 

 fraction of the serum as contrasted with the albumin fraction which 

 remains in solution. The precipitate may be dissolved in physiological 

 saline and the portion in solution may be restored to its original salt 

 concentration, thereby forming isotonic solutions of the two protein frac- 

 tions. Ferrata found that neither of these components in the presence of 

 an amboceptor was capable of producing hemolysis, but that if both were 

 added, sufficiently soon after dialyzation, hemolysis would take place. 

 Brand studied this phenomenon further and found that both fractions 

 are equally thermolabile and because of activities which he discovered, 

 named the fraction contained in the globulin precipitate " mid-piece " and 

 that in the albumin " end-piece." If the amboceptor- cell mixture is 

 treated first with mid-piece, no hemolysis occurs, but if end-piece is then 

 added, hemolysis occurs as it would have in the original amount of com- 

 plement. If the end-piece is first added and later the mid-piece, hemo- 

 lysis will occur, but in very much smaller degree than if the entire 

 complement had been used. Zinsser found, however, that when mid- 

 piece and end-piece are mixed and then added to the sensitized cells, 

 the hemolytic effect is reduced and is considerably less than if mid-piece 

 is added before end-piece. It has been found that the mid-piece may 

 enter into combination with the sensitized cells at o C, but the end- 



