610 REPORT OF THE COMMISSIONER OF AGRICULTURE, 



After remaining in the iueuhator for a diiy it was found that the virus exposed to 

 the disinfectant for 1^, 2, 7, 10 and 20 minutes had been destroyed, the tubes remain- 

 ing permanently clear. The others contained pure cultures of the liog-cholera 

 bacterium. 



Tlie bacterium may be thus killed by solutions of mercuric chlo- 

 ride, which do not destroy spores. Koch found that anthrax spores 

 may remain in solutions of 1 : 50000 for over GO minutes without losing 

 their capacity for germinating. That all of the germs were not de- 

 stroyed in the. above experiment does not Aveaken the conclusion. 

 They were undoubtedly incrusted with blood and cellular elements, 

 so that the disinfectant could not exert its full power directly upon 

 them. Koch, on the other hand, used spores from cultures only. 

 The experiment demonstrates the absence of anj^ resistant spore state 

 in the tissues of tlie animal, but points out the necessity of consider- 

 ably increasing the strength of disinfectant solutions in endeavoring 

 to destroy the bacteria in nature, inasmuch as we have to deal with 

 other things besides the germs themselves, which neutralize much 

 of the disinfecting power. 



Is there any resistant spore state in the life-history of the bacte- 

 rium of hog-cholera? 



Stained in dilute solutions of aniline colors the bacterium from 

 the tissues of animals which have succumbed to the disease stains in 

 such a way as to leave the impression that it contains an endospore. 

 A narrow band of stained substance bounds an oval pale body, which 

 is but slightly tinged. It appears that a rather resistant envelojDS 

 prevents the coloring matter from x)assing readily and quickly into 

 the interior of the bacterium. 



If a drop from a recent liquid culture be suspended from the lower 

 surface of a cover-glass and examined in a glass cell with a homoge- 

 neous immersion objective and small diaphragm, the following* ap- 

 pearances are worthy of record: The bacteria in the center of the 

 drop of culture fluid are in very active motion and quite small. If 

 the periphery of the drop be examined there will be found a dense 

 layer of bacteria caught there by the slow desiccation and conse-. 

 quent contraction of the drop. These, some of which are still mov- 

 ing slowly, are larger than the forms in the center of the drop. As 

 the drying proceeds and the film of water becomes thin the bacteria 

 appear to be made up of a distinct dark border surrounding an almost 

 transparent bodj'-. In most forms there is a slightly thicker border 

 at the ends than at the sides of the short rod-like bodies. When 

 stained slightly this border takes tlie stain well, while the body of 

 the rod remains pale. The fact that the structural and color pict- 

 ures correspond is strong evidence that the microbe possesses a 

 rather dense membrane, which in optical section is seen as a narrow 

 dark border. 



The form and size of the bacteria under consideration depend upon 

 the culture medium and upon the ago of the culture. The appear- 

 ance which they present in the animal tissues is very closely simu- 

 lated in liquid media, more especially beef infusions with peptone. 

 When grown on gelatine or potato the appearance just described 

 cannot as a rule be made out, as the bacteria are ajjt to be smaller. 



The foregoing facts incline us to believe that wo have no true spore 

 Btate to deal with in this microbe, but perhaps a membrane, which is 



