562 E. I. WERBER 



we must admit that Forster's idea although at the time ex- 

 pressed in a rather vague manner, is characterized by great 

 foresight. One gains this impression particularly from Wolff's 

 ('13) excellent summary on the biological relationship between 

 embryo and mother during pregnancy. 



This relation is, according to Wolff, particularly intimate in 

 man, for the nutrition of the embryo is directly from the mother's 

 blood. It is also of especial interest in such cases where, owing to 

 pathological conditions, some toxic products of metabolism ac- 

 cumulate in the mother's blood. That the embryo is influenced 

 by such alterations of maternal blood, is, according to this author, 

 very plainly evidenced by clinical as well as experimental pa- 

 thology. Thus it has, for instance, been found that the fetus of 

 a nephritic mother may suffer from oedema and ascites (Sitzen- 

 frey '10). The same obtains also in the animal experiment, if 

 pregnancy is induced in a nephrotomized female. 



As a very interesting illustration of the intimacy of physio- 

 logical relation between fetus and mother in man may be con- 

 sidered the observations recorded by Kehrer.^ According to 

 this author bile acids and bile pigments can in the animal experi- 

 ment not cross the placental barrier and thus they never reach 

 the embryo, while in man the observation can be made that 

 children of women suffering from jaundice during pregnancy 

 may have jaundice at birth. 



Such data would seem to leave no doubt that the mammalian 

 embryo is sometimes subject to influences of a disturbed maternal 

 metabohsm. Whether all products of a deranged metabolism 

 will have a deleterious effect on the embryo is a matter which, 

 of course, needs investigation. In the preceding I have shown 

 that if two substances known to occur in disturbances or carbo- 

 hydrate metabolism, viz. butyric acid and acetone, be allowed 

 to act on fertilized teleost eggs, the latter will develop into 

 various monsters very strikingly resembling the monsters of 

 man and other mammals. Even teratomata have thus been 

 produced. These results would seem to leave little room for 

 doubt that mammalian monsters may often be due to a coinci- 



' Quoted from Wolff ('14). 



