161 



If we would make use of sensitiveness to dessication as a 

 character of Pfeiffer's bacillus it would thus seem to be ap- 

 propriate to employ a period of 24 hours for the drying process 

 (with the proviso that similar temperature and humidity con- 

 ditions prevail to those mentioned above). 



In examining the duration of life of the various strains 

 of Pfeiffer's bacillus I have, in a large number of cases, used 

 cultures which after having been incubated 1 — 3 days, were 

 preserved in the cold room (at about 5°). Almost all the 

 strains mentioned on p. 110 were examined, some of them twice. 

 The greatest length of life was observed in I 71 and 1 91 

 which still gave a good growth after having been cultivated 

 24 hours in the incubator and then remaining a month in 

 the cold room. But 6 days later these cultures did not give 

 growth. 



Distinct individual differences were noted between the 

 various strains but as they seemed to be rather inconstant 

 the experiments will not be given in detail. 



The very limited resistance against heat, drying, and keeping, 

 excludes the presence of spores in the cultures, unless in 

 this instance they recpuire very different conditions for their 

 development than the ordinary vegetative forms. One might 

 imagine however that spores might be formed under special 

 conditions of cultivation. I have therefore made the following 

 tests. 



All the strains mentioned on p. 110 were inoculated on plates 

 of Fildes agar, and kept in the incubator for 8 days. The plates 

 were then immersed in a water bath at 54° for 40 minutes, in the 

 manner previously detailed. In no case was there growth in the 

 cultures made from them. 



Twenty-four hour cultures of the same strains were also ino- 

 culated on to plates prepared with salt solution (V2°/o salt) and 

 agar. These plates remained in the incubator for 24 hours and 

 were afterwards heated to 55° for half an hour. There was no 

 growth from any of these plates on subcultivation. 



Fermentation Tests. 



In October 1918 the strains I 1—17 were inoculated on 6 sets 

 of agar plates containing litmus, and glucose, laevulose, lactose, 

 saccharose, maltose and mannite respectively. Small drops of horse 



11 



