NATURAL RESISTANCE 181 



of cytost intoxication — in this case the so-called tox- 

 emia of pregnancy. On a similar basis we may explain 

 the occurrence of such toxemias in pregnant women; 

 for in their case it has long been known that the human 

 embryo becomes completely embedded in the uterine 

 tissue, and this must take place by a mechanism similar 

 to that in the monkey. For obvious reasons, embryolo- 

 gists have not been able to follow this process in the 

 woman as Hartman has done in the monkey; but in 

 this instance it does not appear fallacious to argue by 

 analogy. 



The concept of toxemia outlined above is easily sub- 

 jected to experimental verification; for symptoms 

 similar to those accompanying the toxemia of preg- 

 nancy should be elicited by the parenteral introduc- 

 tion of cytost into pregnant animals. This has been 

 shown by the writer (1921, 1922) as follows: When 

 homologous cytost preparations were injected intra- 

 peritoneally into healthy pregnant cats, the animals 

 showed signs of acute nausea within from thirty sec- 

 onds to two minutes after the injection, and violent 

 retching continued for thirty to fifty minutes, fre- 

 quently accompanied by symptoms of eclampsia. As 

 has been stated previously, such injections, if con- 

 tinued, may induce abortion. On the other hand, injec- 

 tions of heterologous cytost into pregnant cats does 

 not result in the onset of any of these difficulties. 

 These results seem to prove unquestionably that the 

 toxemia of pregnancy is actually due to the release 

 of cytost brought about by the activities of the devel- 

 oping embryo in utero. 



In a normal pregnancy the majority of the symp- 

 toms of toxemia disappear long before the end of 



