140 DISEASES OF SWINE 



nite. However, it seems to play some part in the resistance of the 

 body to infections, and in all the acute infectious diseases it is the 

 usual rule to find marked changes in this organ. This is the case 

 not only in swine, but holds equally true in practically all species 

 of animals and in man as well. 



So in hog-cholera, which is undoubtedly an acute infectious 

 type of disease, it is only reasonable to expect to find marked 

 changes in the spleen. It is found on examining the spleen, espe- 

 cially in those cases which run an acute course, that there is marked 

 enlargement and swelling of the organ. The entire spleen is en- 

 gorged with blood, and when examined with the hand will be found 

 to be quite softened and pulpy in consistence. 



On cutting into the substance of the spleen it is found that the 

 normal scarlet or pink color has disappeared, and, instead, the 

 organ appears darkened and congested. There is often a consid- 

 erable accumulation of decomposed blood in the organ, and this 

 drips from the cut surface as a dark almost tar-like fluid. 



If we prepare a portion of the spleen for microscopic examina- 

 tion and, after proper staining, examine under the miscroscope, 

 we will find that there have been marked changes in the minute 

 structure of the organ. The normal splenic pulp has been largely 

 replaced by a broken-down collection of destroyed gland cells and 

 disintegrated red blood-cells. The blood-vessels in the organ are 

 dilated and engorged with blood. There is pouring out of blood- 

 corpuscles in enormous numbers into the surrounding splenic pulp, 

 and the entire picture is one of very pronounced and severe degen- 

 eration and destruction. 



In some cases the congestive changes in the spleen are not so 

 marked, and we have instead more of a parenchymatous degen- 

 eration of the organ, with swelling of the individual spleen cells; the 

 nucleus of the individual cell is crowded to one side, the cell bodies 

 show numerous small albuminoid granules throughout their sub- 

 stance, and the entire cell stains poorly with the ordinary stains. 

 In many cases there appear in the center of the cell small droplets 

 of fat, which have commenced to form as the result of beginning 

 fatty degeneration. 



These marked changes in the spleen would seem to point 

 very strongly to the conclusion that hog-cholera is a germ-produced 



