TECHNIC. 325 



the same degree as when the fresh defibrinated 

 blood, containing serum., is used. These results 

 seem to show definitely that phagocytosis depends 

 on the power of the opsonins to affect the bacteria 

 in some peculiar manner. 



Later experiments showed that the opsonic opsonic 

 power of the blood varied in the course of disease 

 just as is found in the case of other immune sub- 

 stances. The relation of such an abnormal opsonic 

 power to that of normal serum was designated as 

 the opsonic index. 



The Wright technic deals with three factors as Tecimic. 

 will be apparent from the above: leucocytes, bac- 

 teria and serum. 



Leucocytes. The leucocytes are obtained in dif- 

 ferent ways according to the kind employed. Human 

 leucocytes are obtained by puncturing the lobe of 

 the ear or tip of the finger with a small lancet 

 and catching the blood in a 1 to 1.5 per cent, 

 solution of sodium citrate in 0.85 per cent, sodium 

 chlorid solution. The amount of blood necessary 

 is usually small, about 1 c.c. and 10 c.c. of citrate 

 solution is required to keep the blood from clot- 

 ting. By centrifugalizing, the corpuscles are 

 separated from the citrate solution and the cor- 

 puscles washed by pipetting of the supernatant 

 fluid and replacing it with physiologic salt solu- 

 tion. Two such washings are made and then the 

 pearly-colored blood cream containing the leuco- 

 cytes is removed from the surface of the red cells 

 for use. 



Serum. This is obtained as for agglutination 

 or other tests. 



