624 PROGRESS OF SCIENCE IN THE CENTURY. 



amalgamation, unification, with (it may be) result- 

 ing integration as the social relations became more 

 subtly interwoven. 



In both processes the factor which biologists 

 call " isolation '' may operate ; thus the expansion 

 of groups may involve the geographical isolation of 

 some of their offshoots, and the consolidation of 

 groups may mean a restricted range of cross-fertili- 

 sation. 



Of no little importance, as it seems to us, is some 

 consideration of in-breeding (i. e., pairing within a 

 limited range of relationship) and cross-breeding 

 (i. e., the pairing of members of distinct stocks). 

 Thus Dr. A. Eeibmayr has argued that the establish- 

 ment of a successful tribe or race involves periods of 

 in-breeding, with the effect of " fixing " or engraining 

 constitutional characteristics, and periods of cross- 

 breeding, with the effect of promoting a new crop 

 of variations oi* initiatives. 



While there is — and, at present, must be — great 

 diversity of opinion as to the best means of securing 

 a healthier " social organism,'^ there is practical un- 

 animity as to the end in view, which may be ex- 

 pressed in the v/ords with which Mr. Spencer closes 

 the third volume of his Principles of Sociology 

 (1897): — "Long studies . . . have not caused 

 me to recede from the belief expressed nearly fifty 

 years ago : ^ The ultimate individual will be one 

 whose private requirements coincide with public 

 ones. He will be that manner of man who, in 

 spontaneously fulfilling his own nature, incidentally 

 performs the functions of a social unit, and yet is 

 only enabled so to fulfil his own nature by all others 

 doing the like/ " 



