CLASSIFICATION OF PNEUMOCOCCI 127 



blood. The patients' serum was added to heavy suspensions of 

 pneumococci. These materials used in small quantities and in con- 

 centrated form gave a rapid end result, and because of its reli- 

 ability Noble used the method to measure agglutinins in the blood 

 of pneumonia patients during serum treatment. 



SLIDE AGGLUTINATION 



In 1929, Sabin 12<u introduced his simple rapid "Stained Slide" 

 microscopic agglutination test. Briefly, the test consisted in in- 

 jecting the sputum into the peritoneal cavity of a mouse, then a 

 few hours later puncturing the abdominal wall, withdrawing a 

 small amount of peritoneal exudate, mixing it with the diagnostic 

 serums of the various types in separate drops on the same slide, 

 and finally smearing, fixing, and staining the mixtures. The slide 

 was examined under an oil immersion lens for evidences of agglu- 

 tination. Sabin also applied this method to the determination of 

 antibody in the blood of pneumonia patients for the control of se- 

 rum administration, as proposed by Park and Cooper. 1057 A drop 

 or more of the patient's blood was withdrawn into a capillary tube, 

 and after coagulation and contraction of the clot, the tube was 

 centrifuged and a minute amount of the extruded serum spread 

 with a loopful of a saline suspension of a heat-killed culture of the 

 type for which agglutinins were sought. The film was air-dried, 

 stained for one-half minute with fuchsin, and examined micro- 

 scopically. When checked against the Noble and macroscopic ag- 

 glutinin methods, this test was found by Sabin to be two and 

 one-half to three times more sensitive when standard diagnostic 

 type serums were used for comparison. In a paper published in 

 1930, Sabin 1202 gave further details and refinements of the tech- 

 nique. In addition to using the method for the control of serum ad- 

 ministration, he found it to be of service in detecting the presence 

 or absence of active infection in man. 



Armstrong (1931 ), 22 giving Sabin credit for originating the 

 method, introduced a slight modification of Sabin's technique by 



