CHAPTEE XIII. 



INTKA-TJTEKINE INFLUENCES. 



THE abnormal peculiarities occasionally observed 

 in animals at the time of birth, that are not recog- 

 nized as family characteristics, have been popularly 

 attributed to some mysterious influence of the imagi- 

 nation of the mother in the process of intra-uterine 

 development. 



This influence is supposed by many to be exerted 

 not only in mammals, where the most intimate rela- 

 tions are known to exist .between the mother and the 

 embryo during the period of utero-gestation, but also 

 in fowls, where the egg is separated from the mother 

 before the slightest indications of embryological de- 

 velopment can be detected. 1 



The following cases, which have been reported as 

 illustrations of this influence, will be sufficient to show 

 the kind of evidence on which it rests, and the varied 

 results it is claimed to produce : 



1 " Cyclopaedia of Anatomy and Physiology," vol. ii., p. 475 ; Wright's 

 " Book of Poultry," pp. 131, 314. 



It has even been assumed that birds, in the process of incubation, 

 exert an influence upon the eggs they are hatching that is sufficient to 

 modify the characters of the progeny. In artificial incubation, however, 

 and when the eggs of one species are hatched by another, the inherited 

 characters are not modified. 

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