127 



In recording the occurrence of Pfeiffer's bacillus in healthy 

 persons a distinction was made between „typical" and ^aty- 

 pical' strains but a detailed explanation of these terms was 

 postponed till later. We have now come to the point at 

 which a discussion of them is appropriate. 



In fig. 1, plate I will be seen the symbiosis tests of the 

 white air coccus and 7 different strains of Pfeiffer's bacillus. 

 A striking difference will be immediately observed between 

 the two upper strains (I 1 and I 5) and the others (H 318, 

 II 332b, GP 1, GP 2, GP 5), the symbiotic growth of the 

 first two being considerably more marked and of a purer 

 white colour than that of the last 5. Further the two first 

 strains' growth is of a soft, homogeneous consistence, (which 

 naturally cannot be seen in the illustration), so that one can 

 move an inoculation needle about in it, just as if it were a 

 mass of cream. In contrast to this the growth of the other 

 strains has a harder, more friable consistence, so that by 

 prodding it with an inoculation needle one breaks it up into 

 small pieces which can be pushed along the surface of the 

 agar without further disruption. These strains on the whole 

 are also prone to grow in separated colonies, even with liberal 

 inoculation. The reason for this it that only comparatively 

 few of the inoculated bacilli develop. 



I have called those strains of Pfeiffer's bacillus with the 

 first kind of growth, „typical" and the others „atypical".* The 

 justification for these terms is firstly, that this distinction in 

 the manner of growth is usually so pronounced that it forces 

 itself on the attention, and indeed even raises the question 

 whether we have not to do with two different species of bac- 

 teria. The macroscopic appearance and the consistence of 

 the culture are largely made use of as a means of recognition 

 of bacterial species. Secondly it has been found that the „aty- 

 pical" strains are almost exclusively met with in non-influenza 

 patients, and every factor which 'affords a distinction between 

 Pfeiffer's bacilli in influenza and Pfeiffer's bacilli in other diseases 

 and in healthy persons, must be utilised. In order to avoid 

 misunderstanding it is again expressly stated that it was not 



* Other authors have used these designations in another sense: 

 typical = non-haemolytic, 

 atypical = haemolytic haemoglobinophilic bacteria. 



