GLOSSARY 



LYMPH GLAND. An organ in which lymphocytes are difTerentiated. 

 LYMPHATIC. A vessel that transports lymph. 



LYMPHOCYTE. A non-granular white blood cell; a non-pigmcntcd or colorless blood 

 cell CJ. LEUCOCYTE and ERYTHROCYTE. 



M. Abbreviation for meter. 



MACRO-. Combining form, meaning "large." CJ. MICRO-. 



MALE GAMETE. See SPERMATOZOON. 



MALNUTRITION. A condition resulting from any deficiency in nourishment. 



MAMMARY GLANDS. Glands that secrete milk; characteristic of mammals. 



MANDIBULATE. Possessing jaws, or mandibles, and thus able to bite. 



MATRIX (/;/. MATRICES). That which encloses anything; the intercellular material 

 of some sustentative tissues; the part of a chromosome surrounding the gen- 

 onemata. 



MATURATION. I'he process of maturing or difTerentiation of the germ cells. See 

 GAMETOGENESIS. 



MEIOSIS. The process by which the number of chromosomes is changed from the 

 diploid to the haploid number; brought about by two nuclear divisions follow- 

 ing the growth period during gametogenesis. CJ. MITOSIS. 



MEROGONY. A form of asexual reproduction involving multiple fission, characteristic 

 of the so-called merozoite stages' of some sporozoan parasites. Often referred 

 to as schizogony. 



MESENCHYME. Loosely arranged cells of irregular shape which are relatively undif- 

 ferentiated and give rise to diflferent tissues; of mesodermal origin. 



MESENTERY. A double layer of cells connecting the visceral and parietal peritoneum 

 and serving as a support for the coelomic organs. 



MESO-. Combining form, meaning ''middle." 



MESOBLAST. One of two cells in schizocoelous eucoelomate animals, from which 

 proliferate the masses or rods of mesoderm cells later hollowed out to form the 

 coelomic pouches. 



MESODERM. The germ layer that is localized between the ectoderm and endoderm. 



MESODERMAL SOMITES. Compact, similar groups of mesodermal cells lying along 

 each side of the neural tube. 



MESORCHIUM {pi. MESORCHIA). The mesentery supporting a testis. 



MESOVARIUM (/V. MESOVARIA). The mesentery supporting an ovary. 



META-. Combining form, meaning behind or bevond in position, or later in time. 



METABOLIC CELL. A cell that is not in the process of division; sometimes called a 

 resting cell. 



METABOLISM. The fundamental manifestation of life in cells; a collective term for 

 the chemical reactions in cells. (J. ANABOLISM and CATABOLISM. 



METAGENESIS. A tvpe of life cycle in which a .sexually reproducing organism arises 

 from and gives ri.se to an asexually reproducing organism. 



METAMERE. See SOMITE. 



METAMERISM. The condition of being divided into a number of similar parts, ar- 

 ranged in linear series and called metameres or somites. 



METAMORPHOSIS. The alteration of structure that an animal undergoes after it 

 hatches; specifically, the transformation of a larva into an adult. 



METAZOA [sino. METAZOON or METAZOAN). Multicellular animals. CJ. PROTOZOA. 



METER. A measure of length equal to 39.37 inches. 



MICRO-. Combining form, meaning "small." CJ. MACRO-. 



MICRON. Unit of measurement in microscopv; 0.001 millimeter. 



MIGRATION. A movement of animals into a new locality, usually in search of food. 



MILLIMETER. The thousandth part of a meter; the tenth part of a centimeter; 1 inch 

 ec|uals 25.4 millimeters. 



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