292 PKINCIPLES OF STOCK-BREEDING. 



present themselves, which enable us to distinguish, 

 one after another, the characters of the order, the 

 family, the genus, the species, the variety, the sex, 

 and the individual the more special features progres- 

 sively evolving themselves out of the more general, 

 which is the expression of the law of development, 

 common to all organized beings." * 



If the process of development is arrested in the 

 early stages of embryonic growth, the foetus, from the 

 imperfection of its organization, may in many respects 

 resemble some of the inferior animals. 



The arrest of development at an early period may 

 prevent the formation of any vestige of a particular 

 organ ; or, if it occurs at a later period, the organ may 

 be rudimentary. 



Any severe shock of the nervous system of the 

 mother, whether by fright or otherwise, may impair 

 the process of nutrition, and thus produce an arrest of 

 development in the entire embryo or some of its 

 parts. 



The rudimentary or imperfectly-developed organ 

 may, however, attain nearly its natural size, as its 

 growth may continue after the cessation of the devel- 

 opmental process. 



It is likewise probable that the habitual mental 

 condition of the mother may have an influence upon 

 the nutrition of the embryo, and thus interfere with 

 its development. It is well known that " a fit of 

 passion in the nurse vitiates the quality of the milk 

 to such a degree as to cause colic and indigestion (or 



1 Carpenter's " Human Physiology," p. 987 ; " Comparative Physi- 

 ology , p. 124. 



