19 



does not increase its streptococcidal power, as shown by experiments by 

 Hektoen & Ruediger. 



We know that untreated bacteria are not taken up by washed leu- 

 cocytes in Na Cl solution or in heated serum, and hence there should be 

 no reduction in the number of streptococci in a test tube containing a 

 suspension of washed human corpuscles in salt solution or in heated 

 serum. The following experiment shows that this is the case : 



Experiment 3. Ten c. c. of blood was drawn from a vein at the 

 elbow of a scarlet fever patient, defibrinated, centrifugated and the 

 serum drawn off. The corpuscles were washed twice in a large amount 

 of NaCl solution, and 0.5 c. c. of the washed corpuscles placed into 

 each of three small tubes containing 0.5 c. c. of normal serum, 0.5 

 c. c. of heated serum (58 degrees for one-half hour) and 0.5 c. c. of 

 salt solution, respectively. The tubes were inoculated with one loopful 

 of streptococcus culture, and two loopfuls from each were plated at in- 

 tervals with the results shown in Table 10. 



TABLE 10. 



Colonies on Glucose Agar Plater.. 

 Strepto- 

 cocci. Immed. 5 hours. 24 hours.. 



300 Washed corpuscles + serum 1500 7 21 



300 Washed corpuscles + heated serum 1400 5000 Many 



300 Washed corpuscles + NaCl solution 1700 3500 Many 



300 Serum 1200 1400 Many 



The importance of opsonin in the destruction of streptococci by hu- 

 man leucocytes is further shown by the fact that the defibrinated blood 

 from two obstinate cases of post-scarlatinal nephritis had no streptococci- 

 dal powers, although in one of the cases the leucocyte count was 14,000. 

 When the blood from these patients was centrifugated and the corpuscles 

 suspended in serum from a patient who was convalescent and had no 

 nephritis, the resultant suspension had a small degree of streptococcidal 

 power, as shown by Table n. 



The interesting fact came to light in these experiments that the 

 combination "convalescent washed corpuscles plus nephritis serum'' has 



TABLE 11. 



Colonies on Agar Plates. 

 Strepto- 

 cocci. Immed. 2 hours. 5 hours.. 



298 Convalescent blood 800 450 14 



298 Nephritis blood 720 1900 6000 



298 Nephritis corpuscles -j- cony, ser 850 500 540> 



298 Conv. washed corp. -f Neph. ser 725 GOO 01 



