The General Infections oj the Genitalia of Swine 739 



lustrative of some of the fundamental principles of genital 

 infections and the physiology and pathology of reproduction 

 in general. 



The embryonic sacs of swine testify emphatically to es- 

 sentially universal intra-uterine infection of significance. 

 Embryologists have described the necrotic tips of the em- 

 bryonic sacs of swine as "normal" by which the reader as- 

 sumes this necrosis to be physiologic. Bonnet apparently 

 regards the phenomenon as the result of pressure necrosis. 

 That is, the embryonic sac outgrows the length of the uter- 

 ine (cornual) cavity and, pressing the apices of the sacs 

 either against the apex of the cornu or against adjacent em- 

 bryos, by pressure cuts off the nutrition of the chorion, so 

 that the part dies. Numerous facts contradict this assump- 

 tion. It is generally contrary to physiologic development 

 that an organ or tissue should undergo dry necrosis and be- 

 come in effect a permanent (during gestation) foreign body. 

 Instead useless organs or tissues usually undergo cellular 

 disintegration with resorption. The necrosis at the poles of 

 the embryonic sacs is inconstant in occurrence and extent. 

 It is not always present. The necrosis increases with the 

 advancement of pregnancy, as would be expected of a 

 chronic infection. When some of the embryos are necrotic, 

 the necrosis of the tips of the other embryonic sacs contain- 

 ing live embryos is more extensive than that observed in 

 uteri where all embryos are apparently healthy. From 

 whatever angle the phenomenon is viewed, it is difficult to 

 escape the conviction that the necrosis commonly present at 

 the two poles of each embryonic sac of swine is the result 

 of a chronic intra-uterine infection which existed, or was 

 introduced, at the time of coitus, and that death of swine 

 embryos is ordinarily referable to an extension of such polar 

 necrosis. The path of invasion appears to be through the 

 amnion from the necrotic area, after which the embryo 

 swallows the bacteria and the active invasion of the embryo 

 itself begins within the alimentary tract. 



There are many scattered records of abortion in swine, 

 but in most reports it is not made clear what the observers 



