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prepuce of 15 dogs. From each dog a blood agar plate and a Fildes 

 plate were inoculated. From 9 of the 15 dogs colonies appeared 

 usually in large numbers which grew rather more slowly than 

 Pfeiffer's bacillus and in contrast to these, better on blood 

 agar than on Fildes agar. After 3 days' incubation the colonies 

 on blood agar were about 2 mm. in diameter, of a homo- 

 geneous grey colour, and almost soft though little tenacious 

 in consistence. They departed considerably in appearance from 

 Pfeiffer's bacillus. On Fildes plates the colonies had the 

 appearance of small Pfeiffer's bacillus colonies. In several 

 cases well developed granulations were seen. On microscopic 

 examination Gram negative rods were observed, usually rather 

 polymorphic, varying from coccus-shaped forms to rather long 

 curved rods. 



They failed to grow on ordinary and ascitic agar but they 

 could easily be cultivated on the same media as Pfeiffer's 

 bacillus. Decolorisation of the blood pigments was never ob- 

 served either on solid or liquid media. 



They were also compared with Pfeiffer's bacillus in a 

 number of different ways. 



They did not differ from Pfeiffer's bacillus in the 

 following points. 



1. In the dependence upon haemoglobin. Like Pfeiffer's 

 bacillus they grow well on blood agar, haemoglobin agar (with 

 a liberal amount of haemoglobin), Fildes agar, Levinthal agar, 

 and „choco!ate agar", but not at all on ordinary and ascitic agar. 



On 1. XI. 21. — after they had been grown for 16 months 

 — all the 9 strains were inoculated on agar containing lo/ 

 ferratin (prepared from pig's liver according to Schmiede- 

 berg's directions). Neither these strains nor three of Pfeif- 

 fer's bacillus grew. 



On inoculation of the same 12 strains on agar with gra- 

 dually diminishing content of pepsin-digested blood practically 

 no difference could be observed in the „haemoglobin" require- 

 ments of the two bacterial groups. None of them grew on 

 „haemoglobin-free" agar. 



2. They do not produce haemolysis on blood agar. This 

 was tested repeatedly, the last time in Nov. 1921, both on 

 ordinary blood agar and on Fildes agar with the addition 

 of lOo/o blood. 



