COHESIVE POWER OF SOCIAL LIFE 265 



I. The Completion of the Social Blastoderm. 

 With increase in population, migrations, and coloniza- 

 tions, man had at last, within the nineteenth century, 

 covered all the habitable surface of the globe with a 

 virtually continuous blastoderm, to use an embryolog- 

 ical term, or at least with an anastomosing network of 

 human beings, which were everywhere within reach 

 of one another; all of them moving more or less freely 

 to and fro, and mingling with one another in social 

 and reproductive intercourse. 



It is true that the discrete elements in this stream- 

 ing human plasmodium, its individuals, families, 

 tribes, and races, are separated by countless cleavage 

 planes of habits, prejudices, and long established cus- 

 toms; by arbitrary territorial boundaries rupturing, or 

 bending in and out, under the varying osmotic pressure 

 of rising and declining populations; by semi-perme- 

 able rivers, plains, and forests; or by impassable na- 

 ture-barriers, oceans and mountain ranges, ancient and 

 forbidding. But on the other hand, between the larger 

 blood-islands of social life, lie the open gateways of 

 terrestrial architecture, permanent channels, and stand- 

 ing invitations to social and commercial circulation. 

 No animal in the history of organic evolution, nor man 

 himself, has ever before attained this world-wide dis- 

 tribution and this degree of freedom in social inter- 

 course. 



2. The Increment of Power. The increase in the 

 amount of energy at man's command, or that he was 

 able to utilize for moving, or conveying himself and 

 his properties from place to place, was chiefly due (i) 

 To greater food supplies derived from domesticated 



