218 



The Circumscribing and Grouping of Haemoglobinophilic 



Bacteria. 



We have now studied four of the bacterial groups that 

 are generally included under haemoglobinophilic bacteria: Pfeif- 

 fer's bacillus, B. haemoglobinophilus canis, haemolytic haemo- 

 globinophilic bacteria, and Bordet's bacillus, and we have seen 

 that the dependence on „haemoglobin' is a character which is 

 constantly present in every strain of the first two groups and 

 is very easy to demonstrate. It is therefore right to use this 

 property as a distinguishing epithet, that is to say as a limi- 

 ting quality for a number of otherwise more or less distinct 

 bacteria. Neither on the basis of my own results nor on 

 that of the other existing contributions could we mention 

 a property which equally well links Pfeiffer's bacillus with 

 other organisms in a large group. Particular attention has 

 also been paid to the morphology, pathogenicity, and occur- 

 rence, but it follows perfectly well from the above that none 

 of these characters would afford so clear and natural a classi- 

 fication. In my experience and that of others the haemolytic, 

 haemoglobinophilic bacteria are characterised by their requi- 

 ring the same haemoglobin derivates as Pfeiffer's bacillus for 

 their growth although this necessity is not so absolute, and 

 also by the haemolysis. This last property must be made the 

 starting point for defining the group, as the haemoglobinophilia 

 which is less developed than in Pfeiffer's bacillus, is neither 

 strong nor constant enough to be used as a primary basis 

 for this purpose. 



Bordet's bacillus diverges so decidedly from these three 

 species as regards nutritive requirements that it ought not 

 to be included under the haemoglobinophilic bacteria, at all 

 events in the true and more restricted meaning of the word. 



Besides these four species „haemoglobinophilic bacteria" 

 have been described under numerous other names, and an at- 

 tempt will now be made to classify them in the most natu- 

 ral manner. 



„The Committee on Classification of the Society of Ameri- 

 can Bacteriologists" has proposed (see Davis (6)) the generic 

 designation „Hemophilus" and has provisionally included in 

 this, — Pfeiffer's bacillus, Bordet' bacillus, Morax-Axenfeld's 



