30 



The remaining 28 strains of Group IV, 11 from lobar 

 pneumonia and 17 from other respiratory diseases, reacted with 

 none of the 12 Group IV type sera, and include therefore an 

 unknown number of serological types. 



The strains of Group IV are probably the common inhabitants 

 of the nose and mouth, but they are evidently capable of pro- 

 ducing both lobar and broncho-pneumonia, as well as other 

 pathological conditions. On the other hand, although my 

 observations are limited, I have so far rarely found Types I 

 and II in any other condition than lobar pneumonia. A Type I 

 strain was found in the cerebro-spinal fluid of a fatal case of 

 meningitis, and in two cases of empyema Type II strains were 

 obtained. During the influenza outbreak, January 1922, Type I 

 was recovered twice and Type II once from cases of influenzal 

 pneumonia. 



The American observers have shown that Types I and II 

 are of rare occurrence in the non-contact normal n6se and mouth, 

 and do not generally persist very long in the sputum after 

 convalescence from lobar pneumonia due to one or other of 

 them. 



Type III more nearly resembles the strains of Group IV in 

 its distribution. It is found in the normal mouth, though perhaps 

 more frequently in some communities than in others. I may 

 give an example of my own experience. At a school where 

 there was an outbreak of influenza, out of 25 post-nasal swabs 

 from schoolboys, 9 yielded pneumococci of Type III. In the 

 present investigation, Type III has been found in 10 out of 

 150 cases of lobar pneumonia, in 5 out of 30 other infections 

 (bronchitis or broncho-pneumonia) ; in 4 of the above cases 

 (viz., 2 lobar pneumonia, 1 broncho-pneumonia and 1 acute 

 bronchitis), it was found in association with pneumococci of 

 Group IV. 



Suggestions for Uniformity in Classification. 

 There is now sufficient accumulation of evidence to establish 

 the three chief Types, I, II and III, defined by the workers of 

 the Rockefeller Institute, as standard types for international 

 purposes. At some future time the question of the nomen- 

 clature of the various types of pneumococci which differ from 

 the three chief types will, no doubt, be considered by the Health 

 Committee of the League of Nations, if, as is desirable, the 

 results of workers in different countries are to be co-ordinated. 

 In their pioneer work the American investigators classed these 

 heterogeneous strains together as " Type IV." Later, they 

 differentiated a number of types which reacted to concentrated 

 Type II serum and designated them IIa, IIb, IIx, &c. In 

 addition, Olmstead* has shown that the majority of the 

 remaining " Type IV " strains in his collection could be classified 

 into serological types. A comparison of the distribution of these 



* Journ. Immunology, ii, p. 425. 1917. 



