date and a suspension of leucocytes in salt solution or in heated serum- 

 have little or no effect on these organisms. The virulent streptococcus 

 is not destroyed by the leucocytic exudate nor by a suspension of leuco- 

 cytes in serum or blood. Smears made in one to two hours from tubes 

 in which there is destruction of cocci show evidence of phagocytosis. 

 Table 2 shows the same experiment as that shown in Table I ; except that 

 guinea-pig's leucocytes and blood were used. With these leucocytes the 



TABLE 1. 



SHOWING THE EFFECT OF RABBIT'S LEUCOCYTIC EX L- DATE AND MIXTURES OF EXl DATE 

 AXD BODY FLUIDS OX STUEI'TOCOCCI. 



Strepto- Immecli- 



eocci. ately. 3 hrs. 18 hrs. 



300 Leucocytic exudate 4GOO 10000 



300 Exudate 58 for half hour 3250 8000 Many 



300 Defibrinated blood 4800 4700 Many 



300 Blood 1 c. c. + exudate 1 c. c 4000 750 1 500 



300 Rabbit serum 4200 4200 Many 



300 Serum 1 c. c. -f exudate 1 c. e 5200 1100 Many 



300 Leucocytes -f serum 5000 800 Many 



300 Leucocytes in heated serum 5500 3560 Many 



300 Leucocytes in NaCl sol 4900 5000 Many 



300 Leucocytes in NaCl sol. -f Sensitized streptococci 570 32 .",000 



324 Leucocyte exudate 420 11 Many 



324 Defibrinated blood 430 700O Many 



324 Blood 1 c. c. -f- exudate 1 c. c 750 540 Many 



324 Rabbit serum 552 0500 14000 



324 Serum 1 c. c. + exudate 1 c. c 320 1 Many 



B104 Leucocytic exudate 3500 3600 Many 



270 Leucocytic exudate 1700 2 Many 



Sources of streptococci: Nos. 300 and 324 from the heart's blood of scarlet 

 fever patients, postmortem. No. B104 from an abscess in a guinea-pig which 

 had been injected with a fungus. This organism has been passed through 78 

 rabbits and is very virulent for both rabbits and guinea-pigs. 



eighteen-hour plates are often sterile, or nearly so, while it is only occa- 

 sionally that they are sterile when rabbit's leucocytes are used. 



Special attention must be called to the fact that the suspension of 

 leucocytes in salt solution destroys many of the sensitized a virulent strep- 

 tococci. These results are therefore in harmony with the work of 

 Wright and Douglas/-' who have shown that phagocytosis takes place only 

 after the bacteria have been sensitized, that is, have been acted on by 

 the opsonin of the serum. There is no phagocytosis in a suspension of 

 washed leucocytes in salt solution or in heated serum, when untreated 



*Proc. of Royal 'Soc., 1903, LXXJI, 357, and J904, LXXIII, 128. 



