144 



of this bacillus I have only seen identical ones in haemoly- 

 tic, haemoglobinophilic bacilli, which will later be discussed. 

 But I have observed quite similar bodies, even highly de- 

 veloped, in Bacillus haemoglobinophilus canis, which will also 

 be referred to in a special chapter, as well as in pure cul- 

 tures of Gonococcus, and sometimes also in Meningococcus. 



In smears from the granular and non-granular parts of 

 the same Pfeiffer's bacillus colony I have been unable to de- 

 tect any difference as regards the appearance and stratifi- 

 cation of individual bacilli. 



A certain heterogeneous appearance assumed by the co- 

 lonies of some strains of Pfeiffer's bacillus, chiefly the „aty- 

 pical", must not be confused with the granular formation 

 described here. The former do not consist of special, well- 

 defined elements, but of a coarse structure of the whole co- 

 lony, the single elements of which are considerably smaller 

 than the granulations. This appearance is undoubtedly as- 

 sociated with a coarse microscopic morphology, especially with 

 the presence of numerous thread forms. 



In the last 3 chapters we have seen that whether we 

 examine the „macroscopic morphology" of a number of strains 

 of Pfeiffer's bacillus (that is to say the appearance of the 

 culture with the naked eye or low magnification) in a sym- 

 biosis experiment on blood agar or in the form of isolated 

 colonies on haemoglobin agar, we shall observe a multipli- 

 city of forms, among which all transitions between the dif- 

 ferent morphological types seem 1 to be represented. I have 

 sought in vain to discover a definite connection between the 

 individual characters such as the appearance of the growth 

 on blood agar, the size of the colonies, the degree of trans- 

 parency, the occurrence and arrangement of granulations. On 

 the whole there seems to be a rather free combination of the 

 several characters. What we presumably can rely upon is the 

 rough division into „typical" and „atypical" cultures. Schema- 

 tically the 2 groups may be characterised thus: 



