INSTITUTIONAL AND PRUDENTIAL SELECTION. Ill 



We may also assume that increased segregate fecundity and vigor 

 will make the multiplier for pure-breeds = 2, and the multiplier for 

 cross-breeds = i. And when another ten generations have passed, 

 still higher degrees of segregation will be the natural result. 



Conclusion. — We have now approached in three different ways 

 the proof of cumulative advance in a set of innate qualities, which 

 by their combined action produce in moderate degress both positive 

 and negative segregation. The result seems to be that when M 

 by any chance comes to be larger than Mc + m, then the fraction 



Tf-y 5^^ , which gives the ratio of cross-breeds to pure-breeds,* 



M — Mc — m * f < 



becomes a positive quantity, and a given proportion of the whole 

 stock remains unaffected by crossing. This point having been reached 

 the subsequent tendency is toward a constant increase in the segre- 

 gative endowments. 



18. Institutional and Prudential Selection. 



Institutional and prudential selection stand in the same relation to 

 the other forms of reflexive selection that artificial selection holds in 

 relation to natural selection. They are the forms of reflexive selec- 

 tion established in communities of rational beings for the purpose of 

 securing ends that are more or less fully apprehended as the goal. 



It should be observed that inherited instincts have an important 

 part in each of the forms of conjunctional selection, that is, in sexual, 

 social, and filio- parental selection; and again in the forms of impreg- 

 national selection and impregnational isolation just discussed, the 

 coordinations are due to inherited characters, either morphological 

 or physiological; but in institutional and prudential selection the 

 processes are guided by conscious and reflective purpose. It will, 

 therefore, be seen that the conscious regulation of relations between 

 husband and wife, between man and man, or between parents and 

 children, when it affects the form of survival, belongs to either insti- 

 tutional or prudential selection, and not to conjunctional selection 

 in any one of its three forms. In the past history of man the three 

 forms of conjunctional selection have been of prime importance ; but 

 as civilization advances increasing control is given to institutional and 

 prudential selection. Moreover, in the case of civilized man, domina- 

 tional selection through intra-group struggle has in a large measure 

 ceased to be a struggle for life or for the opportunity to have a full 

 share in producing the next generation, and has become chiefly a 

 struggle for influence in society and for escape from certain forms of 



*See Formula (4), on page 105. 



