ANTIBODIES TO PNEUMOCOCCUS 399 



derivatives, since an extract of Type I Pneumococcus failed to 

 prevent phagocytosis of Type III organisms in the presence of 

 Type III antiserum, and vice versa. The inhibiting substance af- 

 fected the organisms and not the leucocytes. Furthermore, the ac- 

 tive principle could be absorbed from extracts by combination with 

 specific immune serum. 



Yamamoto (1929) 1557 " 8 studied the effect of both unheated and 

 heated culture filtrates of pneumococci on spontaneous phagocy- 

 tosis in vivo in the rabbit. The "Impedin," as the author called the 

 inhibitory principle, was without action on the number of mi- 

 grated leucocytes. The injection of heated filtrates affected phago- 

 cytosis in inverse ratio to the duration of previous exposure of the 

 filtrate to heat, the antiopsonic property being completely de- 

 stroyed after thirty to sixty minutes at boiling temperature. 



The action of the specific capsular polysaccharide, so conspicu- 

 ous in the inhibition of other serological reactions between Pneu- 

 mococcus and immune serum, is manifested in its antagonistic ef- 

 fect on opsonins, and is referable to its function of combining with 

 and precipitating the antibodies from serum. In studies on growth 

 inhibition, Sia (1926), 1267 by means of normal rabbit or cat se- 

 rum-leucocyte mixtures, learnt that the presence of a very small 

 amount of purified soluble specific substance from pneumococci of 

 both Types I and II markedly altered the conditions in the mix- 

 ture so that even a small number of avirulent pneumococci were 

 enabled to grow in the presence of serum and leucocytes of animals 

 which ordinarily possess the power to destroy the organisms in 

 relatively large numbers. The action of the capsular carbohydrate 

 was type-specific, and the same neutralizing effect on the growth- 

 inhibitory or pneumococcidal power of normal serum-leucocyte 

 mixtures was exhibited by broth filtrates of cultures of young 

 pneumococci. 



Ward 1480 " 1 confirmed Sia's observations on the specific anti- 

 phagocytic action on blood of soluble specific substance, and found 

 the action more marked in the case of Type III than Type I pneu- 



