15 



blood was added to each tube of melted agar to facilitate the counting 

 of colonies, which often are very small if no blood has been added. 



Table 6 shows that, although human serum in vitro is a good culture 

 medium for streptococci, normal defibrinated blood has a slight strepto- 

 coccidal power. Occasionally we may find a sample of normal blood 

 which destroys many non-virulent streptococci, but the virulent organ- 

 isms usually multiply in this blood. Table / shows that defibrinated 

 blood from patients suffering from an acute infection has a much greater 

 destructive effect on these organisms than has normal blood. (The non- 

 virulent cocci are ingested very freely by the leucocytes while the viru- 

 lent strain is not taken up so freely, as shown by counts in stained 

 smears.) 



TABLE 7. 



THE EFFECT OF DEFIBRIX.VTKH PLOOD FROM CASES OF SCARLATINA, ERYSIPELAS AND 



PNEUMONIA ON STREPTOCOCCI. 



Strepto- 

 cocci. 



300 



?>00 



300 



300 



300 



300 



300 



300 



300 



300 



300 



300 



300 



300 



381 

 B104 

 B104 



381 



381 



381 



381 

 B104 



381 

 B104 



381 



381 



381 



Colonies 



Defibri nated Leucocyte 



Blood. count. Immed. 



Scarlatina I 10500 1100 



II 10600 2000 



III 15000 690 



IV 550 



V 1500 



VI 1000 



VII 500 



VIII 13000 1380 



IV 1200 



X 13400 1250 



XI 1950 



XII 10800 1800 



XIII 1800 



XIV 12300 1500 



III 15000 1200 



IV 600 



V 1800 



VI 220 



VII 130 



VIII 13000 360 



IX 13000 2200 



IX 330 



X 13400 *640 



X 400 



X 320 



XII 10800 200 



XIII 540 



in Agar 

 2 to 3 

 hours. 



270 



18 

 300 

 350 

 32 

 102 

 125 

 245 

 150 

 700 

 300 

 31 



1500 



462 



1800 



51 



41 



1180 



1950 



190 



290 



160 



650 



2000 



900 



Plates. 



5 hours. 

 6 



140 



116 



3 



150 



43 



12 



9 



14 



120 



19 



130 



45 



2 



3500 



415 



5000 



1100 



Many 



Many 



Many 



1500 



2500 



165 



Many 



Many 



Many 



