【正文】 look into the range between total conductance and minimum conductance. The metropolitan and political centers of the world have much in mon with the interdependence, differentiation, and activity of the cortical or subcortical centers of an individual organism. Hence the attention frames found in these spots are the most variable, refined, and interactive of all frames in the world munity. At the other extreme are the attention frames of primitive inhabitants of isolated areas. Not that folk cultures are wholly untouched by industrial civilization. Whether we parachute into the interior of New Guinea, or land on the slopes of the Himalayas, we find no tribe wholly out of contact with the world. The long threads of trade, of missionary zeal, of adventurous exploration and scientific field study, and of global war reach far distant places. No one is entirely out of this world (p. 87). Among primitives the final shape taken by munication is the ballad or tale. Remote happenings in the great world of affairs, happenings that e to the notice of metropolitan audiences, are reflected, however dimly, in the thematic material of ballad singers and reciters. In these creations faraway political leaders may be shown supplying land to the peasants or restoring an abundance of game to the hills. When we push upstream of the flow of munication, we note that the immediate relay function for nomadic and remote tribesmen is sometimes performed by the inhabitants of settled villages with whom they e in occasional contact. The relayer can be the school teacher, doctor, judge, tax collector, policeman, soldier, peddler, salesman, missionary, student。 in any case he is an assembly point of news and ment.More detailed equivalences The munication processes of human society, when examined in detail, reveal many equivalences to the specializations found in the physical organism and in the lower animal societies. The diplomats, for instance, of a single state are stationed all over the world and send messages to a few focal points. Obviously, these ining reports move from the many to the few, where they interact upon one another. Later on, the sequence spreads fanwise according to a fewtomany pattern, as when a foreign secretary gives a speech in public, an article is put out in the press, or a news film is distributed to the theaters. The lines leading from the outer environment of the state are functionally equivalent to the afferent channels that convey ining nervous impulses to the central nervous system of a single animal, and to the means by which alarm is spread among a flock. Outgoing, or efferent, impulses display corresponding parallels. The central nervous system of the body is only partly involved in the entire flow of afferentefferent impulses. There are automatic systems that can act on one another without involving the higher centers at all (p. 88). The stability of the internal environment is maintained principally through the mediation of the vegetive or autonomic specializations of the nervous system. Similarly, most of the messages within any state do not involve the central channels of munication. They take place within families, neighborhoods, shops, field gangs, and other local contexts. Most of the educational process is carried on the same way.A further set of significant equivalences is related to the circuits of munication , which are predominantly oneway or twoway, depending upon the degree of reciprocity between municators and audience. Or, to express it differently, twoway munication occurs when the sending and receiving functions are performed with equal frequency by two or more persons. A conversation is usually assumed to be a pattern of twoway munication (although monologues are hardly unknown). The modern instruments of mass munication give an enormous advantage to the controllers of printing plants, broadcasting equipment, and other forms of fixed and specialized capital. But it should be noted that audiences do talk back, after some delay。 and many controllers of mass media use scientific methods of sampling in order to expedite this closing of the circuit.Circuits of twoway contact are particularly in evidence among the great metropolitan, political, and cultural centers of the world. New York, Moscow, London, and Paris, for example, are in intense twoway contact, even when the flow is severely curtailed in volume (as between Moscow and New York). Even insignificant sites bee world centers when they are transformed into capital cities (Canberra, Australia。 Ankara, Turkey。 the District of Columbia, .). A cultural center like Vatican City is in intense twoway relationship with the dominant centers throughout the world. Even specialized production centers like Hollywood, despite their preponderance of outgoing material, receive an enormous volume of messages.A further distinction can be made between message controlling and message handling centers and social formations. The (p. 89) message center in the vast Pentagon Building of the War Department in Washington transmits with no more than accidental change ining messages to addressees. This is the role of the printers and distributors of books。 of dispatchers, linemen, and messengers connected with telegraphic munication 。 of radio engineers and other technicians associated with broadcasting. Such message handlers may be contrasted with those who affect the content of what is said, which is the munication of editors, censors, and propagandists. Speaking of the symbol specialists as a whole, therefore, we separate them into the manipulators (controllers) and the handlers。 the first group typically modifies content, while the second does not.Needs and valuesThough we have noted a number of functional and structural equivalences between munication in human societies and other living entities, it is not implied t