OPSONINS AND OPSONIC INDEX 89 



appearance of malignant sarcomata. An attack of erysipelas (it 

 has long been observed) occurring in a patient with some malig- 

 nant disease, has the effect of causing a disappearance, or retro- 

 gression, of the tumors. Artificial infection with streptococci 

 was then practiced with the idea that it might produce the same 

 effect. But this was found to be dangerous. Coley prepared 

 toxins of streptococci by allowing them to grow with the B. Pro- 

 idgiosus. The mixture after a Jong period of incubation was steril- 

 ized by heat, and the fluid thus obtained was injected into the 

 tissues. Virulent strains of streptococci are used and the dose 

 of the dead culture is about half a drop given under strict anti- 

 septic precautions. The best results are obtained in spindle- 

 cell sarcoma, and the poorest in the melanotic variety. The 

 method by no means should be employed where the tumor can 

 be removed by operation. It cannot supplant the knife, and 

 only in inoperable cases or as a supplementary treatment where 

 other forms of treatment are employed, should it be used. 



Opsonins and Opsonic Index 



Peculiar substances in blood serum have been called by Wright and Doug- 

 lass opsonins (Greek: prepare food for) . If fresh blood is mixed with an emul- 

 sion of some bacteria and then incubated for half an hour, it will then be 

 found that many of the bacteria are within the polymorphonuclear leucocytes. 

 If the serum is washed away from the leucocytes before adding bacteria, none 

 of the latter will be found within the leucocytes. This proves that the serum 

 has some influence on phagocytosis. In order to show that this effect is on 

 the bacteria rather than on the leucocytes, the bacterial suspension may be 

 treated with some serum for half an hour and then washed free from this 

 serum by means of a salt solution in a centrifuge, and then mixed with some 

 serum-free leucocytes; then it will be found that phagocytosis occurs as before. 

 The bacteria have been "sensitized." According to Wright this action is 

 comparable to cooking or peptonizing. 



Phagocytosis then depends upon the action of serum upon bacteria, 

 which are coped with in the body, first by the action of the serum, and then 

 by the leucocytes. It is thermostabile. 



The quantitative action of phagocytosis may be estimated by Leishman's 

 method. He mixed blood and an emulsion of bacteria in salt solution in equal 



