15 



had no great importance in the diagnosis of individual cases. 

 The theory of the etiological significance of Pfeiffer's bacilli in 

 influenza has therefore had a rather „academic" character; 

 it has been a generally accepted theory of remarkably slight 

 practical importance. 



It must however be stated that there have always been 

 sceptics who have not felt convinced of the truth of this 

 theory. (Elmassian, Rosenthal, Sacquepee, Besancon & de 

 Jong, Ritchie, Kruse (2)). 



As is already evident from the title and introduction, the 

 present work sets out to investigate the occurrence of 

 the haemoglobinophilic bacteria as well as their classifica- 

 tion. 



But this is not two subjects which are independent of one 

 another; on the contrary it is natural to look upon occur- 

 rence as subservient to classification, — as one of the fac- 

 tors responsible for the 'latter, since giving an account of an 

 organism's natural habitat is tantamount to describing the cir- 

 cumstances under which it is capable of thriving in nature 

 and this is just as much a characteristic of the microbe as 

 for example its conditions of growth in vitro, its morpho- 

 logy etc. 



For purely practical reasons it will be convenient, both 

 in the review of the literature, which will be given first, and 

 in the subsequent report of the author's own investigations, 

 to deal first with the occurrence and afterwards with the 

 classification. The conditions relating to the occurrence can 

 then also be grouped under the latter. 



The review of other authors' experiences may be divided 

 up as follows: 



First of all Pfeiffer's fundamental paper as well as other 

 investigations during the pandemic 1889—92 are recounted 

 (pp. 17-20). 



Then a resume is given of the views which suggest them- 

 selves concerning the occurrence of Pfeiffer's bacilli under 

 various conditions on the basis of all the available literature 

 (pp. 20-24). l 



As an illustration of this resume an abstract of the lite- 



