151 



croscopic and microscopic morphology, so that cultures with 

 an atypical macroscopic appearance also usually had an atypi- 

 cal microscopic appearance, that is to say, consisted of coarse 

 markedly polymorphic elements, while the macroscopically and 

 microscopically typical cultures usually consisted of small 

 elements without excessive polymorphism. 



As an example, it may be mentioned that, in the inoculations 

 of 6 — 10. IX. 1921, out of 46 macroscopically typical growths, 42 

 were also microscopically typical; 3 were rather polymorphic 

 without being distinctly coarse; 1 was noted as ,, polymorphic" at 

 the first examination and as ,, typical" at the second. Out of 17 ma- 

 croscopically atypical only 4 were microscopically typical, the other 

 13 being polymorphic" or coarse". 



Relation to Oxygen. 



In the chapters on haemoglobinophilia and symbiosis a 

 detailed account is given of the relation of the Pfeiffer's bacilli 

 investigated to the conditions of growth which are particu- 

 larly characteristic to this bacterium. 



We will now discuss the relation of Pfeiffer's bacillus to 

 2 other chemical factors, the concentrations of oxygen, and 

 hydrogen ions, and also a physical one, — the temperature. 



Pfeiffer's bacillus is generally regarded as a decided aerobic 

 organism. According to Scheller (5) it never thrives at the 

 bottom of a stab culture. Experience is divided however, on 

 this point. In agar with Hommel's haematogen Huber obtained 

 growth all along the course of the needle in a stab culture, but 

 he also states it was the only medium! in which Pfeiffer's 

 bacillus could grow in stab culture. According to Kamen (1), 

 Park & Williams and Rivers & Leuschner, it can grow ab- 

 solutely anaerobically. See also Spooner, Scott, & Heath. 



In the autumn of 1918, I myself only obtained growth 

 on the surface of stab cultures of the strains I 1—5 in agar 

 with haemolysed blood. Later on however I m'ade stabs of 

 numerous strains on Fildes agar in test tubes and I regularly 

 got a good growth along practically the whole course of the 

 needle 



That Pfeiffer's bacillus thrives best in an abundant supply 



