632 Our Surroundings 



Meridians: Imaginary lines on the earth's surface extending directly 

 from pole to pole. 



Metamorphic rocks (met-d-mor'fik) : Rocks formed from sedimentary 

 rocks under high pressure and its resulting heat. Marble is an example. 



Metamorphosis (met-d-mor'fo-sis) : A marked change in the form of 

 a living organism by a natural process of development, as the change 

 of a caterpillar to a butterfly. 



Metazoa (met-d-zo'd) : Many-celled animals. Man and all of the higher 

 animals are metazoa. 



Meteor (me'te-or) : A luminous body moving rapidly through the upper 

 atmosphere; a shooting^star. 



Meteorograph (me'te-dr-6-graf ) : An instrument which records atmos- 

 pheric pressure, rainfall, temperature, and humidity. 



Meteorology (me-te-or-ol'o-ji) : The science of the weather. 



Methyl alcohol (meth'il) : A poisonous alcohol made from wood fiber; 

 wood alcohol. 



Microbe (mi'krob) : A germ. 



Microorganism (mi-kro-or'gan-iz'm) : An organism too small to be seen 

 without a microscope. 



Microphone (mi'kro-fon) : The part of a radio sending set that receives 

 the sound waves to be broadcast. 



Micropyle (mi'kro-pil) : A little opening in a seed through which pollen 

 grains grow into the ovule, and through which the hypocotyl comes out. 



Microscope (mi'kro-skop) : An instrument which makes minute objects 

 visible by means of lenses. 



Midrib: The central or main rib of a leaf. 



Migrate: To go from one climate to another at certain seasons of the 

 year, as the seasonal migration of birds. 



Milky way: A luminous cloud-like band composed of millions of faint 

 stars, seen stretching across the sky at night. 



Mineral: Any substance that is neither animal nor vegetable. 



Mixture: A physical combination of two or more elements in which 

 none of them loses its identity. 



Molar: A tooth with a broad, rough, uneven surface; adapted for crush- 

 ing and grinding food. 



Mold: A low form of plant life belonging to the fungus class. The 

 mold which forms on bread is an illustration. 



Molecular theory (mo-lek'u-ldr) : The theory that all matter is com- 

 posed of tiny^particles called molecules. 



Molecule (m6re-kul) : The smallest particle into which a substance can 

 be divided and still be the same kind of substance. 



Momentum ( mo-men' turn) : The combined effect of the weight and 

 speed of a moving body which makes it difficult to stop. 



Monocotyledon (mon-o-kot-i-le'd^n) : A plant having one cotyledon, 

 or seed leaf, such as corn. 



Monoplane: An airplane with a single pair of wings. 



Moon: A spherical body which revolves about the earth and shines by 

 the reflected light of the sun. 



Morphine (mor'fin) : A narcotic drug made from opium. 



Morse code: An alphabet in which combinations of dots and dashes 

 represent letters and numbers. Used in sending telegraph and wireless 

 messages. 



Motion pictures: Pictures showing successive positions of moving fig- 

 ures and objects. When projected upon a screen in rapid succession 

 they give the impression of natural and realistic motion. 



