The units and groups of units of the future social organism, being dependent upon each other, must be coordinated in their activities to do the best team-work, as we have already explained, and it is now possible to predict where the nerve units will congregate. Again, we must go to the animal organism for facts which explain the evolution of society in this regard. In the lowest organisms there are no specialized nerve cells, but it is believed that all the cells are connected by protoplasmic filaments which keep them in touch with each other; indeed, it may be more than mere touch, for there is some evidence that the filaments are really extensions of the protoplasm of the cells which really never separate entirely. Even plant cells are connected by what act as nerves, and some, if not all, plants are thus more or less "sensitive" to stimuli - some highly so.

As organization progressed, and some cells specialized in this coordinating duty, they collected in groups scattered throughout the body, but in the highest animals efficiency demanded that most of them be grouped in one mass, the brain, though there are still small groups or ganglia in other parts of the body, in the separate organs. This seems to be the direction of the evolution of the organization of humanity, and it follows from the tendency of nations to specialize on what they can do best.

We have seen that this tendency has made the nations of the world dependent upon one another as separate commensal organisms, but in time the ultimate result is bound to make them parts of one organism, in which each nation will really be an organ or gland of the greater organism. Already we find one "nation" producing most of the meat, another the coffee, another the wheat, and so on, precisely as the glands produce things needed by the body. The Philippines will eventually supply enough hemp to drive out all substitutes. There is a certain grade of long, fine and strong cotton fiber that can be grown in no place on earth except a limited region in our South, and it cannot be woven into fine cloth except at certain places in England, where the atmosphere is constantly of a certain humidity, for otherwise the fibers break in the course of spinning and weaving. These two areas, then, are already two organs in the present weakly organized union between England and the United States.

Civilization's dependence upon trade, to keep alive the separate organisms, is quickly becoming the dependence of parts of one whole, and is creating this new kind of commensalism similar to that existing between the parts of the body. It has become more evident in the past century because of the increasing efficiency of transportation, a growth which progresses with the organization, as it is really the cause of it. We have shown how transportation has caused supersaturation, but it is now welding the world together.*

Primitive man depended on his own legs and his sphere of activity was, therefore, very limited, and combinations of more than a few families or clans were impossible. When he subdued horses and draught animals he could travel farther, and greater societies rose. Yet, it was only by the growth of transportation following the invention of the steamboat and locomotive, that modern empires could be cemented together. It also enabled foods to be brought from all over the world, permitting those dense masses in England, for instance, which were wholly impossible before. Modern cities, too, fed from immense areas, were impossibilities until means were invented to bring in the food from farms thousands of miles away. Each spot on the surface of the earth is destined to be devoted to the production of that one thing which it can produce the best, and the people inhabiting it will be fed from areas which can produce food the most economically. The channels of commerce are, therefore, real "arteries," as they are figuratively called. The goods carried are the life blood of each component part of the "international nation." Each new freight car or steamship not only binds the present nations more closely together in mutual dependence, but is an actual step toward the specialization which makes them organs in one organism.

* The subject was discussed by Martin A. Knapp, in his address as chairman of the Section on Social Science of the American Association for the Advancement of Science. (1905 Proceedings).

It is difficult to appreciate the enormous development of transportation. The figures do not convey the proper meaning when we say that railroad stock in the United States alone is worth $17,000,000,000, and that 1,700,000 men are employed. When we add the men engaged in other means of transport, and the merchant classes, it is not far from the truth to say that between every farmer and manufacturer there is a man to transfer food for other necessaries.

This evolution has gone to such an extent that mankind is protecting its channels of trade as carefully as the arteries are guarded in our bodies. By mutual agreement we will not even permit interference by a nation at war, except contraband articles consigned to its belligerent or trade with a blockaded port or besieged place. Belligerents cannot touch the enemy's goods under a neutral flag or neutral goods under the enemy's flag. The nations are even clamoring for the abolition of the right of searching neutral ships in the high seas.

The heart and arterial system of this world organism are already in course of evolution because the people in the Northwestern corner of Europe are seafaring by nature. Of the thousands of vessels going through the Suez Canal three-fifths are British and most of the others are German, French and Dutch, the rest of Europe having little part in it. Norway shows its seafaring abilities in its shipping, and is specializing as a carrier for the rest of the world. Even on ships under other flags it is the rule to find Scandinavians in the crew - Vikings now as ever. The absence of this type from the mass of the Russian nation shows why her navy was inefficient, and why her ambition to be seafaring can never be realized.