BY R. GREIG SMITH. 299 



Two very small quantities (lOc.mm.) of active sera obtained 

 from the Board of Health laboratory were heated and used to 

 agglutinate suspensions of bacteria. Phagocytosis was pro- 

 nounced in both cases. 



The jjhagocytosis of bacteria groivn in active serum. — A small 

 spindle-shaped capsule which had been partly filled with the 

 serum of the first case was infected with Bact. typhi and incubated 

 for four days at 37°. At the time of infection the serum 

 was 10 days old. Another capsule partly filled with serum 

 from the second case was heated at 60° for 15 minutes and sub- 

 sequently infected. This was done upon the day that it was 

 obtained. The two capsules were incubated together, and in 

 both the bacteria grew in clumps or colonies at the surface of 

 the air-bubbles and in the capillary limbs of the capsules. After 

 removal from the capsules, the clumps were washed four times 

 with normal saline. They broke up with difficulty into smaller 

 clumps and sedimented rapidly when centrifuged. Chains of 

 swollen, irregularly staining cells were noted in the clumps grown 

 in the unheated serum, while in the heated serum the clumps 

 consisted of bacteria which although not swollen yet stained 

 somewhat irregularly. 



Bacteria grown in unheated serum of first case Phagocytosis. 



Bacteria grown in heated serum of second case Phagocytosis. 



In all the previous experiments the microbes appeared generally 

 in the films as isolated cells or in groups of a few individuals, 

 while in this experiment they were chiefly in large clumps around 

 which the poly nuclear leucocytes had gathered. It might be 

 reasoned that because some investigators failed to obtain agglu- 

 tination with bacteria grown in immune and therefore agglu- 

 tinating serum, the agglutinated substance is not formed on the 

 microbic cells. Had such been the case, agglutination would 

 undoubtedly have played a very minor part in immunity. But 

 it is not the case, for not only were clumps obtained in unheated 

 as well as heated serum, but the cells grown in the sera were 

 phagocytosed. 



