406 GYNECOLOGY 



any placental lesion is necessary. The placenta appears to be more 

 resistant to some organisms than to others. Thus it is clearly es- 

 tablished that tubercle bacilli rarely pass through it; indeed, cases 

 of Lehmann and others prove that though tuberculosis may begin 

 in the placental tissue, the fetus may not be affected. In this con- 

 nection, however, it must be noted that sometimes tubercle bacilli 

 may be present in the fetus, though no lesions be present, since 

 inoculations of guinea-pigs with portions of the fetal tissues may 

 cause tuberculosis. 



It seems certain that in the great majority of cases the placenta 

 is the sole route by which microorganisms and toxins reach the 

 fetus. It is possible that they may pass through the amnion into 

 the amniotic fluid and thence enter the fetus, but this is probably 

 a very rare mode of injection. Charrin and Duclert's experiments 

 on guinea-pigs suggest that the passage of germs through the pla- 

 centa is helped or retarded by varying conditions of the maternal 

 blood. Thus they found retardation when the maternal system 

 was saturated with corrosive sublimate. When tuberculin, alcohol, 

 lead acetate, or lactic acid were present, the passage of the germs 

 seemed to be facilitated. Neelow has experimented on pregnant 

 rabbits, and states that nonpathogenic organisms cannot pass 

 from mother to fetus. 



The placenta suffices to allow the fetus to grow and thrive in 

 many diseased conditions or malformations incompatible with 

 health or life in the adult. Pathologic conditions affecting the 

 structure and function of the placenta endanger the life of the fetus. 

 In many maternal diseases, doubtless, the fetus is destroyed as 

 the result of changes in the placenta, affecting its structure or func- 

 tion, produced by its resistance to the toxic material in circulation. 



The placenta also acts as the great excretory organ for the fetus. 

 Savory long ago produced tetanus in a pregnant cat by injecting 

 strychnine into the fetus in utero. The passage of other drugs has 

 been similarly demonstrated by others. Charrin holds that toxins 

 placed in the fetus, either directly or by the spermatozoa of the 

 father, may pass to the mother. This might explain certain cases of 

 immunization in syphilis (Colics' law). By injecting diphtheria toxin 

 into the fetus in utero he has killed the mother animal. Guinard 

 and Hochwelker have shown experimentally that the passage of 

 drugs from the fetus to the mother is stopped if the former is killed, 

 and that if the fetus be injected after its death the drug is only 

 found in its tissues. Baron and Castaigne have found that drugs 

 introduced into the amniotic fluid are also transmitted to the ma- 

 ternal tissues, though much less rapidly than when injected into 

 the fetus. If the latter be dead, the substances do not pass to the 

 maternal circulation. 



