Page:Collier's New Encyclopedia v. 06.djvu/232

LEFT MENOPOME 190 MENTAL SCIENCE MENOPOME (men'o-pom), Protonop- sis horrida, a large North American am- phibian in the Salamander order. It is widely distributed in the rivers of the Mississippi basin, and is well known as the "hellbender," "alligator," "water- dog," etc., names which suggest its fierce characteristics. It resembles the sala- mander in form, has four well-developed limbs, and a persistent gill-aperture. It attains a length of 18 inches to 2 feet, and has extraordinary powers of voracity and vitality. MENSA, or MONS (monz) MENSA, one of the 14 constellations which La- caille added to the heavens in connection with his work at the Cape of Good Hope. It is named from the mountain which is a conspicuous feature of the landscape at the Cape. The constellation is a very in- conspicuous one near the South Pole, its brightest star being only of 5.3 magni- tude. It is surrounded by Octans, Hy- drus, Dorado, Volans, and Chamaeleon. MENSTRUATION, a sanguineous flow from the lining membrane of the uterus, regularly returning once a month. It generally begins about the 15th year, indicating pubescence, and terminates about the 45th. It is sometimes pro- longed, but cases are rare in which wom- en above 50 years have borne children. There is, as a rule, no menstrual flow dur- ing pregnancy and lactation. The dis- eases incidental to the woman as a result of menstruation are numerous, the chief being menorrhagia and dysmenorrhcea. A similar flow of blood from the lining membrane of the uterus of oviparous ani- mals. It generally recurs once a year, usually in the spring, though in the case of some animals from two to six times. In those that have undergone a change by domestication, as dogs and cats, the re- currence is usually irregular, depending upon various circumstances, as diet, temperature, etc. MENSURATION, that branch of; ap- plied geometry which gives the rules for finding the lengths of lines, the areas of surfaces, and the volumes of solids. In medicine the term denotes a means for exploring the state of the thoracic and other cavities. MENTAL DEFECTIVES. See IN- SANITY. MENTAL SCIENCE, or PSYCHOLOGY is the science of the mind. The science of the mind is the Latin equivalent for the word, of Greek derivation, psychology. Both are concerned with what is called the spiritual, or non-material, part of the human personality. The great advancement made, since Aristotle, in psychology is found in the laboratory. For the present purpose, it is fitting to refer to the apparatus of such a laboratory in the most general way. The instruments for research, and for measuring the methods and results of research, are numbered by the scores. Among the more important of them are the tambour, an instrument designed to record movements upon smoked surfaces ; the plethysmograph, designed to record the changes in the volume of blood in the arm; the pneumograph, designed to record the breathing movements; and there are also similar instruments for recording movements of the head and of the fingers. In fact, the instruments of the psychological laboratory apply to all senses and to the entire intellectual operations. Mental science, or psychology, whether connected or unconnected with the labora- tory, is divided into several branches. Chief among them are what is known as genetic, structural, and functional psy- chology. Genetic psychology is concerned with the origin and development of the mind. The chief question in this branch is whether the differentiation in the mental processes is quantitative or whether it is qualitative. For instance, does the think- ing or the consciousness of the dog differ in degree or in kind from the thinking or consciousness of man? Under this head also such questions as instinct, habit, and the rate of mental develop- ment, are of primary importance. A second branch of the subject is known as structural psychology, which refers to the mind as a force in and of itself; and functional psychology, a third branch, refers to the operation of this force. The two terms, structural and functional, have the same relation, ap- plied to psychology, that they possess when applied to physiology or anatomy. One of the most important applications of modern psychology refers to measure- ments. These measurements are at once direct and indirect. Direct, they have close relationship to the laboratory, and, in particular, to the measurements of the reactions to light and to sound. In- direct measurement still continues certain forces and conditions of the laboratory, but enlarges the tests unto the use, for instance, of the memory, unto the origin and progress of mental fatigue, and unto certain muscular movements. The element of attention, of association of ideas, of correlation of facts, represent a field in which measurements, both as causes and as results, fill important functions.