FATIGUE. lsn FATS. i.e. memory may be more or less mechanical. Now. the essence of mental work is the sorting and weighing and unifying of material. It is a combining or synthetizing process. The great in- tellect is one that makes clear and comprehen- sive systems of the facts with which it deals; but it differs only in degree from the ordinary mind that plods through its tasks. An adequate test of mental fatigue is, then, a combining or con- structive test. The most satisfactory one so far employed is that used in the schools at Breslau by IE Kbbinghaus. It consists in filling out mutilated texts. The individual is given a printed page, in which .words, letters, and syl- lables are lacking, and is asked to reconstruct it so that it shall make sense. The complexity of the task is suited to the age and general capa- bility of the student. The test is given at various periods during the day. and the measure of fatigue is obtained from the number of omis- sions filled in, the number overlooked, and the number of sentences that make sense. The word 'fatigue' is also used, in various meanings, in the psychology of sensation. Thus, in the Young- Helmholtz theory of vision (see Visual Sensation) it denotes a decreased sus- ceptibility of the retina toward light. When a red surface becomes grayish during continued fixation, the red fibre of the retina is said to be fatigued for red light, and therefore to function- ate less actively than at the beginning of stimu- lation. For this concept of fatigue, the rival theory of Hering substitutes that of adaptation. (See After-Image. ) Fatigue is also applied, less definitely, to nervous processes in the organ of hearing. A tone, e.g. heard continuously for a long time becomes slightly less intensive. Both here, and in sensations of temperature, smell, and taste, where the effect of sustained stimulation is much more noticeable, it is well to substitute the word exhaustion for fatigue. Even in vision, the mental proces-e- aci ipanying decreased excitability are entirely different from the fa- tigue-experience which we have discussed above. Consult: Mosso, La fatigue intellectuelle et physique (Milan, 1894); American Textbook of Physiology, ed. by Howell (Philadelphia, 1898); Titchener, Experimental Psychology (New York, 1001). For the method of exhaustion in olfac- tometry, see Smell. FATIGUE. In military phraseology, the term applied to such duties of the soldier as have noth- ing to do with the carrying of arms. The polic- ing of 'amps or quartern, for instance, is a fatigue duty. FATIGUE OF MATERIALS. See Strength OF Ma ii RIAXS. FATIGUE UNIFORM. See Uniform, Mili- I m;v. FATIMA, f&'tS ma. ( 1 ) The name of Moham- med's favorite daughter. (2) A character in the storj of Aladdin iii the Arabian Wights. (3) Bluebeard's last wife, the only one not mur- iiv him. FATTMITES, or FAT1MIDES (from Fa- tima, daughter of Mohammed). The name of an Arabian dynasty representing the Shiite Beet, which reigned for nearly two centuries over I |.t. Its fo under was Obeid Allah, who as sumed the title of /,'/ Iahdi, or Messiah, and claimed to be the descendant of li and Fatima, the daughter of Mohammed. He established his dynasty at Kairwan, in Northern Africa, in a.d. 909. His successors were El Kasim (c.935), El Mansur (c.945), and El Muizz, or Muizz-ed din (c.952). Muizz conquered Egypt in 909. and founded Cairo as the Fatimite capital. He was fol- lowed by El Aziz (975), El Hakem (Biemr Allah , (996). El Dhahir (c.1020). El Mostansir (c.l035),ElMostali (1094), El Amir (1101), Kl Hafid(1130), El Dhafir (1149), El Faiz (c.ll.'ili. El Adhid (1160-71). In the year 1171, on the death of Adhid, Saladin (Salah-ed-dln) , founder of the Ayubid dynasty, took possession of Egypt. Like all the Mohammedan dynasties, the Fati- mites degenerated after attaining great power. They protected the Shiites, and the Caliph Hakem persecuted the orthodox Mohammedans, or Sunnites, as well as Jews and Christians. He was a relentless tyrant, but claimed to be the tenth and most perfect of the divine incarnations, and attempted, through an academy which he founded at Cairo, to establish a religious cult. (See Druses.) Consult Wiistenfeld, Geschichte der Fatimiden-Chalifen (Gottingen, 1881). See Caliph. FATS (AS. feet, Icel. feitr, Dutch vet, OHG. ft izit, (!er. feist. Felt, fat). An important cIhss of substances found in all parts of the animal organism, although they occur mainly in sub- cutaneous tissue and on the surface of muscles. They are largely taken in ready-formed in the food. Unlike the albuminoids, however, they are also to some extent produced by the animal or- ganism itself. As to their mode of formation, it was for a long time believed that they are de- rived in the body from sugar, starch, and other carbohydrates; in recent years, however, it lias been shown that they are produced by the chem- ical transformation of albuminoids, though the presence of carbohydrates does seem necessary to their formation. The quantity of fat in the human body varies considerably at different peri- ods of life. In the earlier stages of fcetal exist- ence we find scarcely any fat; in new-born chil- dren there is usually a considerable quantity of this substance deposited under the skin, and the organism continues rich in fat till the age of puberty, when a marked diminution of the sub- stance occurs. It again increases about middle life, and then occasionally occurs in great excess; for example, three or four inches of fat are not infrequently found under the skin of the ab- domen of corpulent persons. Extraordinary de- posits of fat in some particular pari of the body are sometimes found both in men and in animals: the remarkable prominence of the buttock in Hottentot women is due to this cause. The uses id' fat in the animal organism are manifold. It plays an important part in the process of cell- formation; it protects the body from external shocks by a uniform diffusion of pressure through the whole adipose tissue; it checks the loss of heal by radiation: it promotes the mobility of various organs, etc. Its chief use, however, con- sists in supplying a great pari Of the heal energy indispensable to animal life, heat being produced in the organism mainly by the combust ion of available fat. A moderate accumulation of fat serves as a store of combustible matter in time of need. A superfluous growth of fatly tissue, on the other hand, is a soiltve of ureal inenll venience, and gives rise to the condition known as obesity. See also Fatti Degeneration,
