Preface v 



the central position in the literature upon genital diseases 

 in animals so long, that anyone attempting to write a sys- 

 tematic treatise in this field must either make infectious 

 abortion the cornerstone or reject it wholly. While in this 

 treatise it is held that all abortions in animals (except those 

 induced surgically) are due to infection, it is denied that 

 such infection is specific, as that term is commonly under- 

 stood in medicine. It is denied as a principle in pathology 

 that conception, parturition, birth, or other physiologic act 

 draws across the path of life an impenetrable barrier to dis- 

 ease. It is held that any infection competent to invade a 

 female may likewise invade a male; if able to invade a preg- 

 nant animal, it may also invade the same animal when non- 

 pregnant ; if it can gain a habitat in the pregnant female, it 

 may persist after parturition ; if it can invade and imperil 

 the life of an embryo or fetus, it may continue through 

 birth and affect the new-born, or may attack the new-born 

 from external sources. Any infection which can invade and 

 injure or kill a post-natal animal, may cause the same in- 

 jury to it while intra-uterine, provided that contact is made. 

 If tuberculosis or syphilis exists in the pregnant uterus, the 

 infection may invade the embryo. There is no evidence to 

 show, and no reason to believe, that any acute infection may 

 not attack and destroy the embryo if the virus is brought 

 into contact with it. It is true that acute infections, when 

 attacking a pregnant female, rarely if ever pass the intact 

 placental filter and reach the embryo. It does not follow 

 that the embryo is immune to the infection, but merely that 

 it is in a hermetically sealed sac, so isolated that the virus 

 fails to acquire contact. 



Although the placental isolation of the embryo is efficient 

 against filterable viruses, the supporters of the "specific in- 

 fectious abortion" theory hold that certain comparatively 

 large bacteria defy this important law, invade the pregnant 

 female, pass directly to the existing embryo, and cause its 

 death and expulsion. But in invading the pregnant female, 

 presumably through the mouth, the infection is alleged to 

 reach the endometrium and embryo without leaving behind 



