162 



blood were put on the surface of the agar, in which the various 

 cultures were rubbed up. Although there was a fairly good growth 

 of Pfeiffer's bacillus no acid production was noted in any of the 

 media in iy 2 days. 



In April 1920, the strains on p. 108 and a number of other 

 cultures from influenzal pneumonia and healthy persons, as well 

 as all the 15 cultures from measles cases, were inoculated on Le- 

 vinthal agar with the addition of litmus and about 0.4o/o of the 

 following carbohydrates: glucose, laevulose, saccharose, and maltose 

 The medium was of such a reaction that the litmus assumed a 

 bluish-violet tint. Although Pfeiffer's bacillus grew particularly well 

 there was not the slightest change of colour during Ihe 4 days' 

 observation. 



Later, a number of experiments were performed in which Fildes 

 agar with the addition of a mixture of phenol red and decolorised 

 china blue was used, which in a rather stronger concentration 

 than that given by Morishima, is extremely sensitive. Unfortuna- 

 tely all these experiments failed. Most of the strains certainly 

 gave a marked acid reaction, but it was very inconstant in Ihe 

 case of surface growths, though more constant in stab cultures. II 

 appeared however that the same indicator change (acid- formation?) 

 could be obtained, not only on agar without sugar added, but 

 even when the agar was prepared from broth which had previously 

 been fermented with Bacillus coli. Whether the change in colour 

 of indicator in the experiments with the „sugarfree" agar was due 

 to glucose, — partly unfermented by the coli bacilli and partly 

 split off from the agar — I cannot decide. We know that abso- 

 lutely sugar-free agar medium cannot be made. Curiously enough 

 Pfeiffer's bacillus in stab culture in the agar prepared from coli- 

 fermented broth produced a considerably greater degree of acidity 

 than a number of other bacteria (various micrococci, dysentery, 

 paratyphoid, Bacillus enteritidis Gartner, Ratin bacillus), which were 

 inoculated in the same way for comparison. Only the two last- 

 named organisms gave a weak change in the acid direction, while 

 Pfeiffer's bacillus caused a marked colour change. 



Although I have not been able to throw much light upon 

 the subject, I do not consider it superfluous to point out, on 

 the basis of these experiments, that in fermentation tests with 

 Pfeiffer's bacillus on agar, it is possible to get even a very 

 pronounced acid reaction where it is not legitimate to assume 

 there has been any fermentation of definite carbohydrates. 



As the fermentation tests on agar were apparently worthless 

 I proceeded to try them in liquid media. 



Broth, previously fermented with Bacillus coli, was inoculated 

 with the „air coccus". In a couple of days' time, lo/o dissolved 



