504 Pneumonia 



of pneumonia. If necessary, the expectoration can be 

 examined by the methods already given for staining the 

 pneumococcus, or rabbits may be inoculated and the organ- 

 ism recovered from the blood. Caution must be exercised 

 in using this means of diagnosis, however, as the organ- 

 ism sometimes occurs in normal saliva, and is a common 

 associated organism in tuberculosis and other respiratory 

 diseases. Wadsworth* has been able to show that agglu- 

 tination reactions can be obtained by concentrating the 

 pneumococci in isotonic solution and adding the serum. 

 The method does not seem easily applicable for diagnosis. 

 Neufeld f and Wadsworth J have also found that when 

 rabbit's bile is added to a pneumococcus culture so as to pro- 

 duce lysis of the organisms, the addition of pneumococcus- 

 immune serum to the clear fluid so obtained results in a 

 specific precipitation. This seems to have little practical 

 importance, however, for purposes of diagnosis. It is, 

 however, of some importance in assisting in the recognition 

 of the pneumococcus and differentiating it from the strepto- 

 coccus, for when the latter organisms are similarly treated no 

 precipitate takes place. 



Buerger found that all pneumococci, irrespective of 

 source, were agglutinated by pneumococcus immune serum, 

 that such serum was capable of agglutinating various pyo- 

 genic streptococci, certain atypical organisms, and certain 

 strains of Streptococcus mucosus capsulatus. The sera of 

 pneumonia patients varies in its power to agglutinate dif- 

 ferent pneumococci; some strains were agglutinated, others 

 not. The sera of normal individuals and of normal rab- 

 bits possess no agglutinating power for pneumococci, the 

 atypical organisms, certain streptococci, and the Strepto- 

 coccus mucosus capsulatus. 



As pneumococci sometimes grow in chains instead of in 

 pairs, and as the capsules are not always more distinct than 

 the capsules that sometimes surround streptococci, it may 

 be necessary to resort to special methods of cultivation for 

 the final determination of the organism. One of the first 

 to be recommended is the use of the blood-agar plate, to 



* "Jour. Med. Research," vol. x, p. 228, 1904. 



t "Zeitschrift fiir Hygiene," 1902, xi. 



J Loc. cit. 



"Jour. Exp. Med.," Aug. 25, 1905, vn, No. 5. 



