Types of Pneumococci 475 



1. The morphology of the two organisms, the pneumococcus tending to be 

 elongate or' lanceolate, occur in pairs and have a capsule. 



2. The more luxuriant growth of the streptococcus in artificial culture. 



3. The ability of the pneumococcus to ferment inulin, which the streptococcus 

 ordinarily fails to do. 



4. The solution of pneumococci within 15-20 minutes by the addition of 5-10 

 per cent, of bile to a fluid culture. 



5. The solution of the pneumococci in 0.2 per cent, sodium chlorate solution. 



6. The production of a reddish hemolytic zone by streptococci and of a 

 greenish zone by pneumococci, about colonies upon blood-agar. 



7. The agglutination of the organisms by antipneumococcus and antistrepto- 

 coccus serums respectively. 



Wadsworth* has shown that agglutination reactions can be ob- 

 tained by concentrating the pneumococci by centrifugalization 

 in isotonic salt solution and adding the serum. Neufeldf and 

 Wadsworth J have also found that when rabbit's bile is added to 

 a pneumococcus culture so as to produce 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 value for purposes of diagnosis, but is useful in assisting 

 in the recognition of the pneumococcus and differentiating it 

 from the streptococcus, for when the latter organisms are similarly 

 treated no precipitate takes place. 



Buerger§ found that all pneumococci, irrespective of source,were 

 agglutinating by pneumococcus-immune serum, that such serum 

 was capable of agglutinating various pyogenic streptococci, certain 

 atypical organisms, and certain strains of Streptococcus capsulatus. 



T^es of Pneumococci. — In the first studies of the comparative viru- 

 lence of pneumococci, Kruse and Pansini|| observed striking differ- 

 ences in cultural, morphological and pathogenesis among these 

 micro-organisms. The matter was puzzling and was not greatly 

 clarified Ijy the studies of Netifeld and Handel** Itseemed curious, 

 that some pneumococci in an avirulent state should be found in the 

 mouths of well persons, that some slightly virulent organisms should 

 be found in the lesions of pneumonia, and that other cultures ob- 

 tained from pneumonia should appear somewhat differently and 

 possess great virulence. The solution of the problem begun with 

 the work of Dochezft and was continued by Dochez and Avery,tt 



Cole,§§ Pisek and Pease,|||| Mitchell,*** Cole.ftt Stillman,ttt 



1 



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

 t "Zeitschrift fiir Hygiene," 1902, xi. 

 t Loc. cit. 



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

 II "Zeitschrift fiir Hygiene," 1892, XI, 279. 

 ** "Zeitschrift fiir Immunitatsforschung," 1909, III, 159. 

 ft "Jour. Exp. Med.," 1912, xvi, 680. 

 it "Jour. Amer. Med. Asso.," 1913, lxi, 727. 

 §§ "New York Medical Journal," 1915, ci, p. i.' 

 Ijll "Amer. Jour, of the Med. Sci.,"i»i9i6, cli, 14. 

 *** "Penna. State Medical Journal," 1917, xx, p. 343. 

 ttt Jour. Exp. Med.," 1917, xxiv, No. 4, 56. 

 %%% "Jour. Exp. Med.," 19x7, xxvi, p. 513- 



