EXPRESSION. .",*] EXTENSION. ,niil,:n"l repetition of movements which under other oonditions were physiologically necessary i /;. . is. The respiratory disturbances of anger and fear, e.g. may be considered as "organic reminis- cences . . . of tlic blowings of the man making a series of combative efforts, of the pantings of one in precipitate flight." (4) Thi principU of the mechanically determined idiopathic effects of the stimulus, i.e. the physiological outpourings of ex- eess of nervous energy through the easiest drain- age channels (of. Wundt's first and Darwin's third law). (5) The principle of the mechanical perpi tuation of emotional reactions which may be called accidental an far as their origin goes. For some of our emotional reactions no plausible rea- son can be conceived. "In fact, in an organism as complex as the nervous system there must be many such reactions, incidental to others evolved for utility's sake, which would never themselves have been evolved independently, for any utility they might possess." In conclusion it may be said that no one of these explanatory series of principles is logically complete. There is need of further observation, and perhaps of a new construction of principles upon the basis of the psychology of action (q.v. ). Consult: Darwin, The Expression of the Emotions in Man and Ani- mals (London, 1890) ; Wundt, Grundziige der physiologischen Psychologie i Leipzig, 1893) ; James, Principles of Psychology (New York, 1890) : Titchener, Primer of Psychology (New York, 1899). See Gesture. EXPULSION (Lat. expulsio, from expellere, to drive out, from ex, out + pellere, to drive). The act of removing one from the possession of real property, or from an office, or from member- ship in a body or association, or of depriving him of a right, privilege, or license. Expul- sion of the first sort is called eviction (q.v.). The manner in which a public officer may be expelled or removed is generally regulated in this country by constitutional or legislative pro- vision. For example, the Federal Constitution secures to each House of Congress the power to expel a member with the concurrence of two- thirds. In the exercise of this authority, it may proceed summarily, and need not observe the for- malities of judicial procedure. Nor does any ap- peal lie from its decision. The same Constitution secures to Federal judges both of the supreme and inferior courts tenure of office during good behavior. Recently many statutes have been passed by Congress, and by State Legislatures, limiting or qualifj'ing the power of removing persons from office in certain lines of the civil service (q.v.). Members of a corporation may be expelled in certain cases, as where they have been convicted of an infamous crime or have been guilty of some corrupt or dishonorable conduct in connection with the affairs of the corporation. A partner cannot be lawfully expelled from his firm, unless the partnership contract expressly authorizes expulsion. In such a case, as well as in all other cases of unincorporated associations, the mem- ber proceeded against is entitled to notice of charges and an opportunity to defend himself, as well as to a fair and impartial decision. See Club. Persons who are not members of a public body or of a private corporation or association may be expelled from its meetings at any time. Even though their attendance has been induced by an authorized invitation, the license or privilege may be withdrawn a1 any moment; and it Hey refuse to leave they may be forcibly removed, The same rule holds good in the case of other meel ings. Those who convene them have the right to expel objectionable persons, provided they use no more force than is necessary for thai purpose. Consult: Thompson, Commentaries on thi I, mi- ni Private Corporations (Saint Louis, IS95); Pollock, Treatise on the Law of Torts (Oth ed., I, on. Ion and New York, 1901). EXTENDED ORDER. See Infantry; TaO- I II S, ,l INIAIIV. EXTENSION (in logic). See Denotation. EXTENSION, EXTENT (Lat. extensio, from extendere, to stretch out, from ex, out -f- tendere, to stretch). The simplest spatial deter- mination of mental processes, as duration (q.v.), is their simplest temporal determination. Not all psychologists are agreed upon the existence of extent as an intrinsic attribute of sensation; but for the present purpose we may provisionally as- sume that extent, in the sense of 'spread out- ness,' is a characteristic feature, at least, of vis- ual and cutaneous and articular sensations. The validity of this assumption will be discussed later. Of the psychological problems concerned with spatial relations, the majority, such as the perception of form, of distance, position, order, arrangement, the geometrical-optical illusions, etc., take us beyond the treatment of extent as an attribute of sensation. Within the sphere of sensation there are theoretically three problems to be solved: (1) that of the smallest noticeable extent; (2) that of the largest noticeable ex- ten! : and (3) that of the just noticeable differ- ence of extents, or the sensible discrimination (q.v.) for extent. These problems must be at- tacked in the sphere both of visual and of hapti- eal sensations, though the latter are. for practical reasons, limited to a single quality, pressure. The second question is at once the least im- portant theoretically and the least difficult of solution. Maximal extent of pressure may be obtained, e.g. by immersion of the entire body in water. The 'maximum visible' is obviously meas- ured by the total area of the 'field of vision.' This embraces for a single eye a region delimited by the following angles (based upon the straight line joining the centre of the pupil with the centre of the 'yellow spot'): outward. 70°-85°; inward, G0°-50°; upward, 45°-S5° ; downward, (15°. Hence the maximal field is, for a single eve, an oval measured by a visual angle of 130°- 135° horizontally, and 110°-120° vertically. The first problem, that of the smallest notice- able extent, brings us to the well-worn question of the 'minimum visible.' Two factors must be constantly regarded: (1) In the neighborhood of the stimulus-limen, extent and intensity play into each other's hands. An imperceptibly small area may become perceptible with increased illu- mination; an imperceptible degree of illumina- tion may become perceptible with an increase in its area. (2) Owing to the error of dispersion (diffusion of stimulation upon the retina), the extent of the object used as a stimulus may not correctly indicate the extent of the stimulated portion of the eye. In the method of Helmholtz the least noticeable visual extent is determined by approximating two luminous points or lines placed at a constant distance from the eye, and
