retards multiplication of virulent streptococci and sometimes kills them. 

 Normal leucocytes in normal serum, and leucocytes from an immune 

 rabbit suspended in normal serum, do not greatly retard multiplication 

 of virulent streptococci. Leucocytes from a normal rabbit, or those from 

 an immune rabbit, suspended in immune rabbit serum rapidly take up 

 and destroy virulent streptococci. The serum has acquired something 

 in the process of immunization \vhich neutralized something in the cocci 

 by virtue of which they were protected against phagocytosis. 



Denys and Marchand* showed that there is better phagocytosis ot 

 virulent streptococci when inoculated into a suspension of rabbit's leu- 

 cocytes in normal rabbit serum to which had been added I per cent, of 

 immune horse serum, than when they were inoculated into the same 

 mixture of leucocytes and rabbit serum with the addition of I per cent, 

 of normal horse serum. 



Bordet* was able to find no protection against streptococci in normal 

 and immunized rabbits and guinea-pigs except that due to phagocy- 

 tosis. If a rabbit was treated with antistreptococcic serum, and later 

 injected with several times the minimum fatal dose of streptococci, the 

 organisms were all taken up by phogacytes and destroyed. In untreated 

 rabbits he also found phagocytosis, but the organisms soon got the upper 

 hand and the rabbit died of streptococcus infection. 



Marchand* studied phagocytosis of virulent and non-virulent strep- 

 tococci, and came to the conclusion that the failure on the part of the 

 leucocytes to take up virulent streptococci depends on a physical property 

 of the organisms and not on a secretion. Tchistovitch** injected rab- 

 bits intravenously with fatal doses of a highly virulent streptococcus, 

 killed the animals in one-fourth to six hours and examined the organs 

 for evidence of phagocytosis. He was always able to find some phagocy- 

 tosis in the lungs and in the livers of these animals, and concluded that 

 this phagocytosis of virulent streptococci may be due to the fact that 

 every culture contained some cocci which are less resistant than others, 

 and that those are the only ones which are taken up by the phagocytes. 



Simon* found very little evidence of phagocytosis, in vitro, when 

 rabbit's leucocytic exudate was inoculated with a non-virulent strepto- 

 coccus. The washed leucocytes suspended in salt solution, and also the 

 cell-free exudate, killed non-virulent streptococci, but not the virulent 

 organisms. Leucocytic exudate mixed with rabbit serum had no effect 



Quoted from Donys, (Vntralbl. f. Bact, 1898, XXIV, 685. 

 **Aun. tie I'lhst. J'Mstour. ISiMi. X, 104, and 18!)7, XI, 177. 

 Archiv. do M('<]. K.\><>r.. ISDN. x. r>r>:j. 

 **An. de 1'Inst. Pasteur. IfXiO. XIV, 802. 

 *Ontnilbl. f. liMkt. V.xn. XXIX. SI and li:',. 



