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bacillus, Ducrey-Krefting's bacillus, and Koch-Weeks' bacil- 

 lus. This genus therefore comprises what we might call the 

 haemoglobinophilic bacteria in its wider sense. It can scarcely 

 be called an obvious natural classification. Apart from the 

 fact that they are Gram negative bacilli, the only features 

 common to the five species consist in that they require various 

 protein products of animal origin in a not too denaturated 

 form. But each species has its own particular nutritive 

 requirements. Media which produce a very good growth of 

 Pfeiffer's bacillus are quite unsuitable for Bordet's bacillus 

 and vice versa. About the same marked differences in food 

 requirements could no doubt be demonstrated between any two 

 of the five species. 



Thanks to Dr. Olaf Blegvad's kindness I have had the 

 opportunity of cultivating Morax-Axenfeld's bacillus from a 

 case of conjunctivitis. The object was to find out how easily 

 this organism could be distinguished from Pfeiffer's bacillus. It 

 was found that good growth took place on Loeffler's serum '3 

 parts horse serum + 1 part broth containing 2o/ glucose; the 

 mixture is coagulated in a sloped position in test tubes), and 

 on ascitic agar, but not on- ordinary agar, Fildes agar, or blood 

 agar. The organism cannot therefore be called haemoglobino- 

 philic. Furthermore it differed very markedly from Pfeiffer's 

 bacillus in its characteristic morphology, and especially in its 

 very intense, clearly defined liquefaction of coagulated serum; 

 a growth on this medium took the form' of a group of deep 

 pits with steep sides. In consequence of the extremely slight 

 resistance of this organism in the cultures, it died before it 

 could be investigated more thoroughly, but the above facts are 

 sufficient to show that it is very different from Pfeiffer's 

 bacillus. 



The same applies to Ducrey's bacillus, about whose nutri- 

 tive wants there have certainly been very different views, 

 but they cannot at any rate be assumed to be identical with those 

 of Pfeiffer's bacillus. It also differs from the latter in its 

 morphology, pathogenic qualities, etc. 



Whether the Koch-Weeks' bacillus ought to be distinguished 

 from Pfeiffer's bacillus has been the subject of much contro- 

 versy which still cannot be regarded as finally settled. Of 

 the authors who have latterly dealt with the question, Pesch 



