59 o THE POPULAR SCIENCE MONTHLY. 



chiefly interested in the study of political government and in his- 

 tory so far as it helps the study of politics. A philosophical stu- 

 dent of such subjects must naturally seek for a theory of evolu- 

 tion. If I may cite my own experience, it was largely the absorb- 

 ing and overmastering passion for the study of history that first 

 led me to study evolution in order to obtain a correct method. 

 When one has frequent occasion to refer to the political and 

 social progress of the human race, one likes to know what one 

 is talking about. Mr. Spencer needed a theory of progress. He 

 could see that the civilized part of mankind has undergone some 

 change from a bestial, unsocial, perpetually fighting stage of sav- 

 agery into a partially peaceful and comparatively humane and 

 social stage, and that we may reasonably hope that the change 

 in this direction will go on. He could see, too, that along with 

 this change there has been a building up of tribes into nations, a 

 division of labor, a differentiation of governmental functions, a 

 series of changes in the relations of the individual to the com- 

 munity. To see so much as this is to whet one's craving for en- 

 larged resources wherewith to study human progress. Mr. Spencer 

 had a wide general acquaintance with botany, zoology, and allied 

 studies. The question naturally occurred to him, Where do we 

 find the process of development most completely exemplified from 

 beginning to end, so that we can follow and exhaustively describe 

 its consecutive phases ? Obviously in the development of the ovum. 

 There and only there do we get the whole process under our eyes 

 from the first segmentation of the yolk to the death of the ma- 

 tured individual. In other groups of phenomena we can only see 

 a small part of what is going on ; they are too vast for us, as in 

 astronomy, or too complicated, as in sociology. Elsewhere our 

 evidences of development are more or less piecemeal and scat- 

 tered, but in embryology we do get, at any rate, a connected story. 

 So Mr. Spencer took up Von Baer's problem and carried the 

 solution of it much further than the great German naturalist. 

 He showed that in the development of the ovum the change from 

 homogeneity to heterogeneity is accompanied by a change from 

 indefiniteness to definiteness ; there are segregations of similarly 

 differentiated units resulting in the formation of definite organs. 

 He further showed that there is a parallel and equally important 

 change from incoherence to coherence ; along with the division of 

 labor among the units there is an organization of labor ; at first 

 among the homogeneous units there is no subordination to sub- 

 tract one would not alter the general aspect ; but at last among 

 the heterogeneous organs there is such subordination and interde- 

 pendence that to subtract anyone is liable to undo the whole pro- 

 cess and destroy the organism. In other words, integration is as 

 much a feature of development as differentiation ; the change is 



