132 THE CAUSATION OF DISEASE. 



mother may bring forth a stout child ; but mere bulk is not a 

 sign of excellence, and we must not too hastily assume from 

 such a case that the state of the maternal nutrition can have 

 little influence on the child. There cannot be the slightest 

 doubt that the general state of the mother's health, by deter- 

 mining the quality of her blood, works a marked effect upon 

 the destiny of the child. 



The mother's blood may likewise affect the foetus by contain- 

 ing some poison, such as the virus of syphilis or scarlatina. 



It is difficult to see how the maternal blood can influence the 

 foetus, except in one of the three ways just mentioned — 

 namely, by being abundant or scanty ; rich or . poor in its 

 proper constituents; or, finally, by containing some noxa. It 

 is not easy to understand how it can convey an impression 

 from a particular tissue in the mother to a corresponding one 

 in the foetus, as must occur (if there be any truth in such 

 cases) when the mother having, let us say, been struck during 

 pregnancy across the face with a rat, the child is horn with 

 a mark corresponding exactly in position. I repeat, one 

 cannot well see how the mother's blood can influence the child 

 so as to bring about such a result. If the maternal im- 

 pression occur before the complete development of the Ovum, 

 the explanation is easy : the tendency. of the ovum is to repro- 

 duce the structure of the mother. Such is the law of heredity. 

 Therefore, if the mother's body undergoes some change in 

 structure before the ovum has ripened (and this takes place 

 just before conception), the child would tend to inherit it; and 

 that mental shocks may work a specific effect upon particular 

 tissues, there can be no doubt. For instance, a woman sees 

 the foot of a child crushed under a gate, and she is forthwith* 

 seized with great pain in her own foot, and • th-is afterwards 

 becomes actually diseased.* Such a local change might so 

 impress the ovum as to lead to a peculiarity in the correspond- 

 ing foot of the foetus developing therefrom. Indeed; this 

 might well occur, even though the mother's foot were ' not 

 obviously affected; for, supposing the doctrine of Pangenesis 

 to be correct, one can understand how the maternal blood 



* See on this subject Tuke's interesting ivork on the influence of the mind 

 on the body. 



