674 



REPORT OP THE COMMISSIONER OF AGRICULTURE. 



The appearances and morphological differences of the microbes dis- 

 covered in hog-cholera and in the infectious pneumonia which we 

 now call swine-plague, are illustrated by the photo-micrographs re- 

 produced in Plates VII, VIII, and IX. The microbe of hog-cholera 

 is seen in Plate VII, Fig. 1, as it appears in the tissues of the body. 

 Most of the germs in this case are sufficiently elongated to be classed 

 as bacilli. In cultures where more rapid multiijlication occurs the 

 microbe is shorter and assumes an oval form (Plate VII, Fig. ^). 

 The microbe from the Nebrasba outbreak of hog-cholera, referred to 

 above, maintained a distinctly rod-like form, however, even in liquid 

 cultures (Plate VIII, Fig. 1). The micrococcus of swine-plague, 

 which is plainly oval in the tissues and in the blood, as shown in 

 Plate IX, Figs. 1, 2, becomes very nearly or quite spherical in liquid 

 cultures (Plate VIII, Fig. 2). This is also very nearly the form seen 

 in gelatine cultures. 



The following comparative table sets forth briefly the differences 

 between the bacterium of hog-cholera and the microbe which has 

 been found associated with pneumonia in pigs and described in the 

 ]Dreceding pages: 



HOa-CHOLEKA BACTERIUM, 



Morphological and biological properties. 



1. Ovals varying in length from 1.2"™ 

 to 1.8"'™. 



2. Stains around periphery, with a 

 slight increase in the width ot the stained 

 border at the extremities ; observed chiefly 

 in the tissues of animals. In cultm-es 

 may stain entirely. 



3. Motile in liquids. 



4. Grows actively on potato. 



5. Resists drying for oneto two months. 



6. Multiplies for a time in drinking 

 water, and remains alive at least four 

 months. 



Pathogenic effects. 



1. In small susceptible animals subcu- 

 taneous inoculation causes but sUght 

 local reaction. 



2. In mice it always produces a disease 

 lasting from eigltt to sixteen days; spleen 

 enormously tuilarged; liver enlarged and 

 containing numerous foci of coagulation 

 necrosis. 



3. In rabbits tlie disease produced by 

 inoculation of small qualities of culture 

 liquid into thigh lasts from six to njnc 

 days. Great enlargement of spleen; en- 

 largement of liver and centers of coag- 

 ulation necrosis. Local lesion: circum- 

 scribed necroeis of muscular tissue. 

 31(Ungs usually h^ve hemorrhagic foci or 

 more extensive lobular pneumonia. 



MICROBE OF PNEUMONIA. 



Morphological mid biological properties. 



1. Ovals varying in length from .8™™ 

 to 1.2'"'". (In both species the size is very 

 variable, according to the stage of growth 

 and division and the culture medium.) 

 This microbe is in general much smaller 

 than the bacterium of swine-plague. 



2. Stains in process of division at the 

 two extremities only. 



3. Non-vwtile in liquids. 



4. Growth on potato fails. Growth in 

 nutrient liquids more feeble; on gelatme 

 almost as vigorous. 



5. Resists drying only a few days. 



6. Does not multiply in drinking water, 

 and is entirely destroyed in a few weeks. 



Pathogenic effects. 



1. Local reaction usually very severe 

 and extensive. 



2. Mice destroyed, bvxt not invariably, 

 in two to six days. No Qharactenstic 

 lesion?. 



8. Same mode of inoculation destroys 

 life in f roni three to six dp-ys. Extensive 

 local sero-s3,nguii}eoviS, later purulent 

 inflltration and thickening; plastic pcri- 

 tonitip; spleen not enlarged. 



