476 Pneumonia 



Blake* and others. The result has been the acceptance of a system 

 devised by Dochez, by which the pneumococci are divided into four 

 groups, known as I, II. Ill and IV respectively. Of these, groups I 

 and II constitute the organisms found in the more benign forms of 

 clinical pneumonia, group III (supposed to be identified with the 

 Streptococcus mucosus of Schottmiiller q.v.) those found in the rapidly 

 fatal variety o'f clinical pneumonia, and group IV made up of mis- 

 cellaneous mildly virulent organisms found in the human mouth and 

 in a variety of pathological lesions other than pneumonia. 



Groups I, II and IV have much the same morphological and cul- 

 tural appearances, but type III is characterized by a much more 

 broad and distinct capsule. 



The chief criterion for the identification of the types, however, is 

 the phenomenon of agglutination, for each organism reacts strikingly 

 to the agglutinating effects, of antiserums produced by organisms of 

 its own type and very slightly to others. Moreover, the reactions of 

 immunity among the organisms are dissimilar among the organisms, 

 the pneumococci of type III being unable to induce the production of 

 any considerable amount of antibody formation (antitoxin). The 

 result is that in endeavoring to treat clinical pneumonia with anti- 

 serum and draw scientific conclusions regarding the eflSciency of 

 the treatment, it is necessary to learn which type of organism is pres- 

 ent and which type of antiserum to administer. Types I and II 

 pneumococci, producing pneumonia that is amenable to treatment 

 by the antiserum, while type III causes a form of the disease that 

 cannot be influenced favorably, the organisms of this type not excit- 

 ing immunity reactions in experiment animals to the (horses) pro- 

 duction of potent antiserum. 



It then becomes important to know how to differentiate the types 

 of pneumococci. To do this requires that serums be prepared by* 

 injecting cultures of the respective strains into animals until strong 

 agglutinating values are obtained. These serums then become the 

 standards of differentiation. 



It is necessary to have on hand agglutinating serum for the various 

 types. These must, at first, be obtained from some laboratory where 

 they are already recognized standards, or one must have for theii' 

 preparation, cultures of the known organisms of the various types, 

 especially types I and II. If the cultures are at hand and it is de- 

 sired to make the serums, that is done by repeatedly injecting a 

 rabbit with first killed cultures, then hving cultures, in increasing 

 doses until a drawn sample of the blood shows a suflScient agglutinat- 

 ing value, when brought into contact with the cocci, to give satis- 

 factory agglutination in considerable dilutions. 



One then proceeds as follows : A portion of the freshly coughed up expectora- 

 tion of the patient, is diluted with physiological salt solution and injected mto the 

 abdominal cavity of a white mouse. In from five to twenty-four hours, as deter- 



*■ "Jour. Exp. Med.j" 1917, xxvi, p. 67. 



