272 



observed, and to indicate in what manner the individual strain 

 is most liable to vary. > 



A few explanatory remarks on some of the illustrations will 

 not be out of place. In the illustrations of I 14 it will be noticed 

 first that while a colony on the haemoglobin agar plate con- 

 sisted of relatively long elements, those on the simultaneously ino- 

 culated blood agar plates consisted for the most part of conside- 

 rably shorter ones and the preparation as a whole showed a more 

 polymorphic picture than in the first case. The two illustrations 

 on the right show a fresh culture on blood agar inoculated from 

 one of these colonies. We see here all gradations) from quite short 

 rods to fairly long threadshaped elements of different thickness but 

 on the whole, rather slender. Similar appearances are observed 

 in several of the other strains illustrated; for instance in I 43 the 

 picture on the left shows the appearance usually described as typical, 

 while in the next culture on the same medium it has already assumed 

 an entirely different aspect. The length of the individual elements 

 is thus an extremely labile character among Pfeiffer's bacilli. 



As a characteristic example of an „atypical" microscopic mor- 

 phology I 28 may be cited which from the macroscopic appearance 

 also was classed as atypical. The characteristics are the great 

 heterogeneity in the size of the elements and, — by no means 

 least — the staining. Side by side in the same preparation are 

 to be seen palestained and very intensely stained elements the 

 latter often being rather larger than the typical forms. The same 

 thing is seen in preparations of bacilli from guinea-pigs which were 

 also all atypical macroscopically. 



Four portions of a preparation of B. haemoglobinophilus cams 

 are also seen. The great variation in the size and staining of the 

 elements is to be noted. On the whole the microscopic picture 

 of this bacterial species corresponded best to the microscopically 

 atypical Pfeiffer's bacilli. 



In the bottommost row preparations of 4 haemolytic strains 

 are shown. Note the very coarse morphology even in cultures 

 which do not exhibit any marked polymorphism. 



The reader is also referred to the remarks on pp. 145-149 

 on the morphological characters. 



