ANTIBODIES TO PNEUMOCOCCUS 365 



Precipitins 



While investigating the massing of pneumococci in the presence 

 of immune serum, Neufeld 974 dissolved the organisms in bile, added 

 the clear solution to the specific serum which had agglutinated the 

 culture, and noted that a particulate substance became micro- 

 scopically visible within a quarter-hour. The aggregations grew 

 and finally formed macroscopic masses of peculiar form and with 

 a hyaline appearance. Neufeld thus showed the close relation that 

 exists between specific agglutination and precipitation, and the ex- 

 periments indicated that both phenomena were due to the same 

 elements in the bacterial body and in the immune serum but, owing 

 to the physical state of the antigenic substance, differed only in 

 the manner of manifestation. In the next year (1903), Wads- 

 worth, 1400 applying Neufeld's technique to saline suspensions of 

 pneumococci and using normal rabbit bile for solution of the or- 

 ganisms, corroborated Neufeld's observations. In order to elimi- 

 nate an}- action of the bile, Wadsworth shook the centrifuged cul- 

 tures with strong salt solution, brought the suspensions to the 

 isotonic point, and filtered them. The filtrate precipitated with im- 

 mune rabbit serum as in the case of the bile solutions of the cocci. 

 The experiment showed that the substance precipitable by immune 

 serum was a constituent of the normal pneumococcal cell and that 

 it could be extracted by suitable solvents. Panichi (1907), 1047 by 

 using filtrates of broth cultures of pneumococci, obtained precipi- 

 tation with serum from rabbits, sheep, and asses previously im- 

 munized with the same organism. The reaction in the different 

 serums varied in degree. A marked reaction was characterized by 

 an immediate opalescence; flakes soon separated, became larger, 

 and settled to the bottom of the fluid in the form of a membrane 

 which did not diffuse on shaking. In milder reactions the sediment 

 was easily dispersed. 



In 1917, Dochez and Avery 321 discovered that the urine of ani- 

 mals experimentally infected with Pneumocoecus and also the 

 urine and blood serum of individuals ill with lobar pneumonia 



