TYPES OF PNEUMOCOCCUS 485 



Dochez and Gillespie 1 showed that the pneumo- 

 cocci may be divided into groups by agglutination and 

 saturation tests (cf. the meningococcus). They divide 

 them into two general groups ; the larger of these con- 

 tains about 80 per cent, of the strains encountered and 

 may be further subdivided into three smaller groups I, 

 II, and III. Group III consists of the type known as the 

 Pn. (Streptococcus) mucosus. The smaller of the two 

 general groups Group IV consists of a series of inde- 

 pendent varieties which possess no cross immunological 

 reactions with one another, nor with the members of the 

 other three groups. The incidence of these groups varies ; 

 in 1,103 cases observed by Spooner 2 29 per cent, were 

 caused by Type I, 21 per cent, by Type II, 11 per cent, 

 by Type III, and 39 per cent, by Type IV. Among a 

 body of Porto Rico labourers, Type I infection was 

 present in thirty-four out of fifty -two cases. 



Lister 3 also showed that pneumonia on the Rand is 

 associated with at least four groups of pneumococci 

 which are additional to those recognised by Dochez and 

 Gillespie. 



The Strep, mucosus may here be referred to. The 

 organism was first obtained by Howard and Perkins from 

 a case of peritonitis, and has since been met with in 

 pneumonia and otitis media. It occurs as a capsulated 

 organism but tends to form longer chains and to grow 

 more freely than the S. pneumonia. The chief points 

 of difference between the two organisms are (1) though 

 apparently capable of causing pneumonia, it is infrequent 

 in this disease ; (2) on subcutaneous inoculation into 

 an animal it tends to cause a mucoid oedema at the 

 site of inoculation; (3) it forms a capsule when grown 



1 Journ. Amer. Med. Assoc., 1913, Ixi, p. 727. 



2 Boston Med. and Surg. Journ., 1920, vol. 182, p. 224. 



3 South African Institute for Medical Research, Hep. No. viii, 1916. 



