FRAENKRUS PNEUMOCOCCUS. 189 



been applied to it. These cocci have round them a capsule, 

 which usually appears as an unstained halo, but is some- 

 times stained more 

 deeply than the *; 



ground of the pre- '/' 



paration. This differ- ' , . '+' 



ence in staining 

 depends, in part at / / 



least, on the amount 

 of decolorisation to \, /* 



which the preparation ' t / /:**' 



has been subjected. *' / "^ 



The capsule is rather 

 broader than the 

 body of the coccus, 'Z^ , 



and has a sharply 

 defined external 



. FIG. 50. t ilm preparation of pneumonic 



margin. 1 niS Organ- S p U j uni( showing numerous pneumococci 



ism takes up the basic (Fraenkel's) with capsules ; some are ar- 



aniline Stains with ranged in short chains 



,. , Stained with carbol-fuchsm. x 1000. 



great readiness, and 



also retains the stain in Grants method. It is the organism 

 of by far the most frequent occurrence in true croupous 

 pneumonia, and in fact may be said to be rarely absent. 



(2) FriedlandeS s Pneumobadllus. As seen in the sputum 

 and tissues, this organism both in its appearance and arrange- 

 ment, as also in the presence of a capsule, somewhat 

 resembles Fraenkel's pneumococcus, and it was at first 

 described as the "pneumococcus." The form, however, 

 is more of a short rod-shape, and it has blunt rounded ends ; 

 it is also rather broader than Fraenkel's pneumococcus. 

 It is now usually classed amongst the bacilli, especially in 

 view of the fact that in cultures elongated rod forms may 

 occur. The capsule has the same general characters as 

 that of Fraenkel's organism. Friedlander's pneumobacillus 

 stains readily with the basic aniline stains, but loses the 

 stain in Gram's method, and is accordingly coloured with 

 the contrast stain, safranin or Bismarck-brown, as above 



