CLASSIFICATION OF PNEUMOCOCCI 129 



The Sabin method, either in its original or modified form, was 

 for some time the one of preference. Among the many satisfied 

 users of the original technique was Brown 151 of the Connaught 

 Laboratories. Heffron and Varley, 602 reporting in 1932 the experi- 

 ence of the Bacteriological Laboratory of the Massachusetts De- 

 partment of Public Health with the Krumwiede, Sabin, and macro- 

 scopic agglutination methods, preferred the Sabin procedure for 

 routine examinations because of the greater number of positive re- 

 sults and the shorter time required. The types as determined by the 

 Sabin method were in all cases checked by agglutination of the cul- 

 ture from the hearts' blood of infected mice. The simple technique 

 was so readily learned by laboratory technicians that Heffron rec- 

 ommended its adoption by diagnostic laboratories. 



Bullowa and Schuman, 185 for the purpose of still further reduc- 

 ing the time factor when a determination of any of the thirty-two 

 types was desired, proposed the pooling of type serums other than 

 I, II, and III. For example, combined lot A comprised Types IV 

 through VIII, while B, C, D, and E included Types IX through 

 XXIII.* With these lots, diluted with saline solution in a ratio 

 of 1 to 10, 1 to 15, and 1 to 25, Bullowa and Schuman made pre- 

 liminary tests and, obtaining a positive result in any group, then 

 tested the strain separately against the monovalent type serums 

 included in that group. These groups may be arranged to fit the 

 prevalence of the various types in different communities or seasons. 



At about the same time, Amoss 13 described another method. A 

 sample of the patient's blood was defibrinated, the serum filtered 

 through celloidin in a Coor's filter, and the filtrate centrifuged at 

 high speed. The filtrate was then concentrated on a steam-bath un- 

 der diminished pressure. To aliquot portions of the concentrate 

 containing the soluble specific substance of Pneumococcus were 

 added equal amounts of specific serum of the three fixed types, and 

 during incubation at 37° in a water-bath readings were made in a 



* Two other lots, F and G, could, of course, be added to include the remain- 

 ing types. 



