Part 3

_Mendel’s Law._ A principle formulated by Gregor Mendel with regard to the inheritance of characteristics. Fenton, following Walter, states it thus: “When two animals or plants unlike with respect to any character are crossed, the offspring of the first generation will be apparently like one of the parents in regard to the character in question. The parent which impresses its trait upon the offspring in this manner is called the _dominant_, while the one that fails to be visibly represented is the _recessive._ When, however, the hybrid progeny of this generation are in turn crossed with each other, they will produce a mixed lot of offspring, one-fourth of which will be like the dominant grandparent, one-fourth like the recessive one, and the remaining half like the parents which resembled the dominant grandparent, yet failed to breed true to it.”

_Mercury._ Of the metallic elements, the only one which is ordinarily found in the liquid state. Quicksilver. Formula: Hg.

_Mesozoic._ Relating to the geological period between the Paleozoic and the Cenozoic.

_Metabolism._ The complete process of building up and breaking down protoplasm in a living organism. The process of digesting and storing nutritive matter and of excreting waste matter.

_Metal._ An element which replaces or is capable of replacing the hydrogen of an acid. One of a class of substances typically ductile, malleable, lustrous, translucent only through very thin layers, conducting heat and electricity well.

_Metaphysics._ The branch of philosophy dealing with knowing and being. This must disappear entirely as science advances.

_Metazoa._ All the complex animals. All the animals except the Protozoa.

_Metric system._ The decimal system of weights and measures generally used in many countries, employed for many purposes by scientists everywhere. A meter is about 1.094 yards. A kilometer is about .6214 of a mile. A cubic centimeter is about .061 of an inch. A kilogram is about 2.204 pounds. The C. G. S. (centimeter-gram-second) system is used in practically every science which deals with space, mass, and time.

_Mho._ A unit of electrical conductivity.

_Microbe._ A very small organism; in popular use, a disease-producing bacterium, a germ.

_Micro-._ Small, in many compounds.

_Mineral._ Pertaining to substances which are not organic. An ore.

_Mineralogy._ The science of ores.

_Miocene._ Relating to the middle division of the Tertiary (geological) period.

_Mitosis._ Cell division and multiplication by the usual process.

_Mixture._ A mass of more than one sort of material which is not chemically compounded or united.

_Molecule._ The smallest amount of a substance which can exist with the properties belonging to the substance.

_Molybdenum._ A metallic element. Symbol: Mo.

_Momentum._ The quantity of motion of a moving body. It is equal to the mass multiplied by the velocity.

_Monadelphous._ With the stamen filaments in a single bundle.

_Moniliform._ Jointed in such a way as to resemble a necklace.

_Monecious._ Hermaphrodite. Having male and female flowers on the same plant.

_Monopoly._ Sufficient control to influence price.

_Monotreme._ One of the lowest order (Monotremata) of mammals.

_Monsoon._ A periodic wind. Specifically, such a wind in the Indian Ocean.

_Moraine._ The mass of earth and other matter deposited by a glacier.

_Morphology._ The study of form (of organisms or of words).

_Motor._ Pertaining to a nerve and an impulse causing motion. Relating to action and the consciousness of action. Pertaining to a muscle causing action. A machine which causes motion, especially such an electric machine or one which is comparatively small.

_Muscle._ A fibrous band or bundle which contracts to produce movement in an animal body.

_Muscology._ The study of mosses.

_Mutation._ A sudden variation which may produce a new species.

_Mycology._ The study of fungi.

_Myriapoda._ A class of arthropods including the centipedes.

_Narcotic._ A substance which induces sleepiness.

_Nascent._ Just beginning, having special properties because of just having been released from combination.

_Neap tide._ The tide at which the high water mark is the lowest.

_Nebular Hypothesis._ The hypothesis advanced by Laplace that (in the words of F. W. Dyson) “a vast nebula--diffused tenuous matter--once extended to the confines of the solar system, and under the influence of gravitation slowly contracted.... As the contraction proceeded the rotation necessarily increased, and rings or other masses were thrown off which collected and formed planets.” Any of several more or less similar hypotheses.

_Nectar._ A sweet fluid produced by plants.

_Neocene._ Relating to the later part of the Tertiary (geological) period.

_Neodymium._ A metallic element. Symbol: Nd.

_Neolithic._ Relating to the later part of the Stone Age.

_Neon._ A gaseous element. Symbol: Ne.

_Nerve._ The rib of a leaf. A vein. One of the fibers or bundles of fibers carrying impulses of sensation and motion.

_Neurosis._ Activity of the nerves. A functional disease attributed to the nerves.

_Neutral._ Neither acid nor basic in reaction. Without sex organs.

_Nickel._ A metallic element. Symbol: Ni.

_Niton._ A gaseous element which occurs in radium emanation. Symbol: Nt.

_Nitrogen._ A gaseous element constituting about four-fifths of the air. Symbol: N.

_Noble metals._ Metals which do not oxidize in air or oxygen. Among the noble metals are gold, silver, and platinum.

_Node._ A knob or root or branch, where a leaf is usually borne. One of the points where the orbit of a planet or comet and the ecliptic meet. A point or line which is at rest in a vibrating body.

_Normal._ Conforming to a standard or type. The normal is not necessarily superior to the abnormal.

_Nutritive._ Of value as food.

_Ohm._ An electrical unit of resistance. The resistance of a circuit in which one volt produces one ampere of current.

_Oligocene._ Of the Tertiary (geological) period, between the Eocene and Miocene.

_Ontogeny._ Individual development.

_Opsonic._ Causing bacteria to be consumed more readily by phagocytes.

_Optics._ The science of light and vision.

_Optimum._ The environment most favorable to the growth of a plant or animal.

_Ordovician._ Relating to the Paleozoic (geological) period between the Silurian and the Cambrian.

_Ore._ A native mineral from which a metal or metals may be extracted.

_Organic._ Living, or derived from a living organism. Relating to all the carbon compounds except a few simple ones. Relating to an organ. Affecting the structure of an organ--of a disease, opposed to _functional_.

_Organism._ An organized being, plant or animal. A living individual.

_Osmium._ A metallic element. Symbol: Os.

_Ovary._ The part of the pistil which contains rudimentary seeds. One of the two reproductive organs in which eggs are produced.

_Overtone._ A tone produced by secondary vibrations, as of segments of a piano wire.

_Ovum._ An egg or female germ. Plural: ova.

_Oxidize._ Combine with oxygen.

_Oxygen._ An important gaseous element. Symbol: O. About one-fifth of the air is oxygen.

_Paleo-._ In many combinations, old, ancient. Also: palæo-, palaeo-.

_Paleozoic._ Of the oldest geological periods. More usually, of the era between the Mesozoic and the Pre-cambrian. The words designating geological eras have been used differently by various scientists.

_Paleontology._ The science dealing with life in former geological periods, with species now extinct but made manifest by fossil remains.

_Palladium._ A metallic element of the platinum group. Symbol: Pd.

_Parallax._ The apparent displacement of an object caused by the actual change in the position of the observer, or by the assumption of two different points of observation. The parallax is expressed in degrees of an angle.

_Paralogy._ Mental illness.

_Parasite._ A plant or animal that derives nourishment or shelter from another upon which, with which, or within which it lives.

_Parthenogenesis._ Reproduction without the union of male and female.

_Pascal’s Law._ The law formulated by Pascal which is fundamental for the mechanics of fluids: A fluid under pressure exerts equal force upon equal areas of surface.

_Pelagian_ or _pelagic_. Relating to the open sea. Pelagic organisms are those which do not approach the shore.

_Penology._ The study of punishment for crime. If this science were studied scientifically, perhaps it would cease to exist.

_Perennial._ Lasting for several years; specifically, lasting for more than two years.

_Phagocyte._ A leucocyte which consumes disease-producing organisms.

_Phase._ The aspect of the moon or of a planet depending on the amount of illumination. Position of variation with regard to a real or assumed starting-point. An individual chemical in a mixture.

_Phenomenon._ Probably more familiar in the plural: phenomena. Something which is perceived by the senses. An event of scientific interest.

_Philology._ The science of language. The philologists have been inclined recently to extend their science, so that it deals with meaning, with folklore or traditional beliefs, and with various other subjects which are more or less closely related to language.

_Philosophy._ Literally: the love of wisdom. Former: the sum of knowledge, a complete system of knowledge, sometimes with emphasis upon its use in regulating human conduct. Philosophy is now primarily ethical. Durant insists that the growth of the various sciences makes it all the more necessary to be concerned with philosophy, which directs the proper use of knowledge. Religion, incidentally, is concerned chiefly with the field indicated for philosophy, not with the ground covered by the various sciences.

_Phonology._ The study of sounds in speech.

_Phosphorus._ A non-metallic element. Symbol: P.

_Photics_ or _photology_. The science of light.

_Photo-._ In compounds, light or photographic.

_Phyllo-._ In compounds, leaf. For instance, Phyllopoda: an order of crustaceans with feet resembling leaves.

_Phylo-._ In compounds, tribe, race. As, phylogeny: racial development, the natural history of a type.

_Phylum._ One of the largest divisions of animals or plants.

_Physics._ The science of matter and energy, not including fields which are considered chemical or biological.

_Pistil._ The female organ of a flower, including style, stigma, and ovary.

_Planet._ One of the bodies which revolve about the sun, including the earth but not comets or meteors.

_Plant._ A living organism which is not an animal. One which does not have sensation or voluntary motion. (This definition must be revised in the light of recent investigations.) Specifically, one of the smaller plants, excluding trees and shrubs.

_Platinum._ A metallic element. Symbol: Pt.

_Pleistocene._ Of the geological epoch before the Recent, in the Quaternary period of the Cenozoic era.

_Pole._ One of the two points in the celestial sphere about which the stars seem to revolve. One of the extremities of the axis of the earth. One of the points on a magnet where magnetic force is manifested. The anode or the cathode of a cell. The extremity of an axis of a spherical or oval cell or organ.

_Politics._ The science of government. Popularly, the art of exploiting democratic citizens, as practiced by office-holders and those who control them.

_Pollen._ The substance discharged from a flower, fertilizing or male grains.

_Pollination._ The carrying of pollen to the pistils.

_Polonium._ A substance found in pitchblende, perhaps an element.

_Poly-._ In compounds, many-. For example, polyadelphous: having the stamens united in three or more bundles. Polyandrous: having at one time more than one husband. Polygynous: having at one time more than one wife.

_Postglacial._ Belonging to a later period than that of the glaciers. Recent.

_Potassium._ A metallic element. Symbol: K.

_Potential energy._ Energy which is latent, not employed or in motion. Energy which a body has because of its position.

_Poundal._ The force which can act upon a pound mass for a second to give it a velocity of one foot per second, or which will give a mass of one pound an acceleration of one foot per second each second.

_Practice._ What is true in theory works out in practice, all due allowances for the influence of other theoretic laws having been made.

_Praseodymium._ A metallic element which occurs in rare minerals. Symbol: Pr.

_Pre-Cambrian._ Relating to the geological eras before the Cambrian period.

_Precipitate._ To change into liquid form. To cause a substance to be deposited in solid form from a solution. To make a dissolved substance insoluble. That which has been precipitated.

_Prehensile._ Used for grasping, suitable for grasping.

_Pressure._ The amount of exertion of force, expressed by the weight upon a unit area.

_Primate._ A member of the highest order (Primates) of mammals, including man and the monkeys.

_Property._ That which belongs to a whole class but is not used to distinguish it from others. Characteristic. A legal right to wealth.

_Protean._ Variable, readily changing form.

_Proteid._ Protein, or member of a special class of proteins.

_Protein._ One of a class of complex organic substances consisting of carbon, hydrogen, nitrogen, oxygen, and, in some cases, other elements. All living cells contain proteins.

_Protoplasm._ The living matter of which all animal and plant cells are formed.

_Protozoan._ A member of the phylum (Protozoa) of animals of the simplest type. A one-celled animal.

_Pseudo-._ In many compounds, false, seeming, similar to.

_Psychiatry._ The treatment of mental disease.

_Psychical research._ The study of phenomena which are not considered by scientists as realities, and which are explained by some persons as due not to natural forces but rather to spirit as opposed to matter. If such phenomena are explained by means of the laws of physics and psychology, there is no need for special “psychical research.” There seems to be no reason why we should postulate spiritual or vital force, even if our knowledge is not yet sufficient to explain all phenomena scientifically.

_Psychology._ The study of the mind; in practice, the study of behavior. Literally: the science of the soul. Perhaps psychology is not yet a true science, but this branch of knowledge is undoubtedly becoming more scientific, in spite of strong philosophical and mystical tendencies.

_Psychophysics._ The study of the relation between the mental and the physical, between psychology and physics.

_Psychosis._ Mental derangement, especially when there is no apparent brain or nerve injury. Consciousness, a conscious process.

_Pteridophyte._ One of a phylum (Pteridophyta) of flowerless plants, including the ferns.

_Pure._ Unmixed, abstract. Pure science deals with general principles, not with particular applications.

_Pyro-._ In compounds, fire-, fever-.

_Quantel._ An elementary entity of matter consisting of positive and negative parts, moving in all directions with the velocity of light, capable of passing through solids. (According to the theory of Langmuir.)

_Quantity._ Anything which can be represented by means of a number. In chemistry, the number of gram molecules.

_Quantum._ The unit of energy transmitted by radioactive bodies.

_Quaternary._ Belonging to the most recent geological period.

_Radical._ Pertaining to a root, growing out of or from a point close to the root. An atomic group which remains unchanged during the ordinary reactions of the compound of which it is a part.

_Radicle._ That part of the embryo of a plant which develops into the main root. A rootlike subdivision of a nerve or vein. Sometimes a mere spelling variation of _radical_.

_Radioactive._ Emitting invisible rays that penetrate opaque matter and produce electrical effects. Radium and some other substances are especially radioactive, but radioactivity is supposed to be characteristic of all substances.

_Radium._ A metallic element. Symbol: Ra.

_Rarefaction._ Making less dense.

_Ray._ A line at right angles to the wave front in which various forms of energy may be transmitted.

_React._ Tend in the reverse direction, enter into chemical combination. Act because of a stimulus.

_Reaction._ An opposing force. A chemical change. The usual nervous response.

_Real number._ A number representing a quantity and one of two opposite directions or senses.

_Réaumur._ A thermometric scale with the boiling point of water at 80 degrees and the freezing point at zero.

_Recapitulation Theory._ The theory which was at one time generally favored by evolutionists, still accepted by many biologists, that ontogeny recapitulates phylogeny; i. e., that the development of the individual is an abridgement of the natural history of the species to which it belongs.

_Recent._ In geology, pertaining to the epoch still in existence.

_Rectify._ Purify, as by repeated distillation. (Important in the chemistry of bootlegging.)

_Reduce._ Remove oxygen, which combines with another substance.

_Refract._ Deflect (light, for example) at an angle. Refraction is due to varying velocity in two mediums.

_Relativity._ Dependence of one quantity or knowledge upon another. The Theory of Relativity formulated by Albert Einstein, based upon the principle that the universe is a four-dimensional (time-space) continuum, includes the conclusions that there is no absolute length, that unobstructed light rays have a constant velocity irrespective of the relative velocity between the observer and the source of light, that the velocity of matter can never reach the velocity of light unless the matter becomes light, that the mass of a body depends on its velocity.

_Reproduction._ Generation, the process of creating offspring of about the same kind as the parents. Apparently the power of reproduction is that which chiefly sets apart the living from the non-living. However, the fact that an individual organism is incapable of reproducing or taking part in reproduction does not show that it is dead.

_Reptile._ One of a class (Reptilia) of animals including snakes and crocodiles. The Reptilia are vertebrate animals which breathe air.

_Resistance._ Non-conductivity, opposition.

_Rheo-_, Stream, Current-, in compounds, chiefly electrical terms. As rheostat: a device for regulating current by controlling resistance.

_Rhizo-_, Root-, in compounds. As, rhizopod: one of a class (Rhizopoda) of protozoa having psuedopodia (“false feet”) which resemble roots.

_Rhodium._ A metallic element. Symbol: Rh.

_Rodent._ One of an order (Rodentia) of mammals, including rats, rabbits, squirrels, and other gnawing animals.

_Röntgen rays_ or _X-rays_. Forms of radiation produced when cathode rays strike the walls of the tube or the surface of a body placed within the tube.

_Root._ A part of a plant, not necessarily but usually growing underground, which attaches it to supporting points and conveys nourishment.

_Rubidium._ A metallic element. Symbol: Rb.

_Ruminant._ One of a division (Ruminantia) of cud-chewing or at least herbivorous mammals with hooves.

_Ruthenium._ A metallic element. Symbol: Ru.

_Salt._ A compound in which all or part of the hydrogen of an acid has been replaced by a metal, or by some other inorganic element or radical. Common salt is one of the general class of salts, and it is known to chemists as sodium chloride.

_Samarium._ A metallic element. Symbol: Sm.

_Saponify._ To turn a fat or oil into soap by combining it with an alkali. The term also includes a wider range of reactions in which hydrolysis is involved.

_Saturate._ To cause a substance to combine with or to absorb the greatest possible amount of another substance. To neutralize.

_Scandium._ A metallic element. Symbol: Sc.

_Science._ Exact, organized, and usually generalized knowledge. A special scientific field or system. Specifically, physical or natural science, not including philology or sociology. It is best not to attach too much importance to such a distinction. See also Art and Common sense.

_Secondary._ In geology, Mesozoic. Relating to reactions or compounds considered less important or less simple than those which are called primary. Of later origin. Induced. Relating to a second part.

_Selenium._ A solid, non-metallic element. Symbol: Se.

_Semen._ The generative fluid of a male animal.

_Seminal._ Relating to seed, semen, reproduction, or germs.

_Seminiferous._ Carrying seed or semen.

_Sensation._ The consciousness of perceiving or seeming to perceive a bodily state or an external object.

_Sentiment._ An emotionally-colored tendency or attitude.

_Sepal._ A segment of the calyx of a flower.

_Septum._ A partition, as between two hollow chambers of an organism.

_Sessile._ Attached directly by the base.

_Sex._ The condition of being male or female or both.

_Sheath._ Membrane, tissue, skin, or other tight-fitting cover.

_Shrub._ A woody plant smaller than a tree. A bush.

_Silicon._ A non-metallic element, solid in ordinary temperatures. The compounds are extremely common. Symbol: Si.

_Silver._ A metallic element. Symbol: Ag.

_Simoom._ A hot, dry wind of western Asia.

_Simple._ Not compound. Consisting of a single cell, element, or individual. Not divided or branched.

_Social._ Living in groups or as a part of a complex organism. Working together. Relating to society.

_Social psychology._ The study of the behavior of human groups. Incidentally, social psychology is an easier subject than individual psychology for the investigator. Where is the man who has never been influenced by other human beings?

_Sociology._ The science of society. The study of the development of social institutions. As sociology exists now, it is scientific only in small parts.

_Sodium._ A metallic element. The compounds are common, including ordinary table salt (sodium chloride). Symbol: Na.

_Soil._ A fine earthy matter on the surface, in which plants can grow.

_Solid._ Relating to the condition of matter in which it has a stable shape and volume, with some elasticity.

_Solution._ A mixture of substances which is the same throughout the mass. We think chiefly of the solution of solids or gases in liquids, but solutions entirely of gases are common, and of solids within solids are possible.

_Somatic._ Relating to the body as a whole or to that part from which no new individuals are developed.

_Sound._ Vibrations produced when some object is set in motion, causing a stimulation of the organs and nerve centers of hearing.

_Species._ A group subordinate in classification to the genus. The members of a species differ only in minor details. In logic, a class may be a species one time and a genus another. In biology, the classes remain fixed. _Homo sapiens_, the class which embraces all mankind, is always a species.

_Specific gravity._ The ratio between the weight of a given amount of a substance and the weight of the same amount of a standard substance, usually water at the temperature where it is densest. For gases, there are various standards.

_Spectroheliograph._ An instrument for photographing the sun by daylight.

_Spectrum._ The image formed by rays of light which are separated into their component wave-lengths. Less frequently, the phenomenon (not entirely visual) produced when other forms of radiant energy are thus split up.

_Sperm._ Semen.

_Spermary._ The organ where semen develops.

_Spore._ A minute organic body that develops into a new individual. A single cell that becomes free and develops independently.

_Sporozoan._ One of a class (Sporozoa) of parasitic protozoans which reproduce by means of spores.

_Sport._ A sudden and striking deviation from type. A mutation.

_Stable equilibrium._ Such a condition in a body that, if suspended like a pendulum and pushed to one side, it resumes its original position immediately below the point of suspension.

_Stamen._ The male (pollen-bearing) organ of a plant.