GLOSSARY 



677 



Lu'mi-nes"cence (L. lumen, light). The pro- 

 duction of hght as a result of chemical reac- 

 tions in cells. 



Lymph (L. lympha, clear spring water). A 

 clear fluid, containing white blood corpus- 

 cles, found in the hmph vessels of the body. 

 Practically, blood without red corpuscles. 



Lym-phat'ic sys'tem (L. lymplia, spring water. 

 Gr. systema, system). A system of vessels 

 and nodes in vertebrates which lead from the 

 tissue spaces to large veins entering the 

 heart; a part of the circulatory svstem. 



Mac'ro-mere (Gr. makros, large; mews, part). 

 The relatively large, yolk-laden cells that arc 

 present during the cleavage stages of certain 

 animals. 



Mad're-po-rite (Fr. madre, mother; Gr. poros, 

 light). The strainerlike cover of the opening 

 to the water-vascular system in echinoderms. 



Mag'got (M.E. mathek). A wormlike legless 

 lar\a of a fly (Diptera). 



Ma-la'ri-a (L. mal, bad; aria, air). Any of sev- 

 eral fevers, each produced by a specific 

 sporozoan parasite which invades the red 

 corpuscles of various mammals and birds. 

 Formerly thought due to bad air. 



Mal-pigh'ian body (After Malpighi, of Pisa; 

 A.S. bodig). Structure in the vertebrate kid- 

 ney composed of Bowman's capsule and the 

 glomerulus. Also called renal corpuscle. 



Man'di-ble (L. mandere, to chew). A jaw; the 

 lower jaw in vertebrates; either jaw of an 

 arthropod. 



Man'tle (L. mantellum, cloak). A fold of the 

 body wall that encloses the soft structures 

 of an animal such as a mollusk and which 

 secretes the shell. 



Ma-nu'bri-um (L. manus, hand). A structure 

 projecting from the middle of the subum- 

 brellar surface of the medusa and bearing 

 the mouth at its free end. 



Ma-rine' (L. mariuus, from mare, the sea). Of 

 or pertaining to the ocean, sea, or other 

 bodies of salt water. 



Mas'ti-ca"tion (L. masticare, to chew). The 

 act of chewing food with the teeth or other 

 mouth parts, as in many insects. 



Ma-ter'nal (L. maternus, of a mother). Per- 

 taining to a mother. 



Ma'trix (L. mater, mother). In animal histol- 



ogy, an intercellular substance. The non- 

 cellular substance of connective tissue as in 

 bone and cartilage. 



Mat'u-ra"tion (L. maturus, ripe). The last 

 stages in the development of gametes, char- 

 acterized by two divisions, in which the 

 number of chromosomes is reduced by 50 

 per cent to the haploid number. 



Max-il'la (L. maxilla, jaw). One of the several 

 mouth-part structures of the crayfish and 

 other arthropods; in the vertebrates, the 

 large bone of the upper jaw. 



Max-ilii-pcd (L. maxilla, jaw; pes, foot). One 

 of the first three pairs of thoracic appendages 

 in the Crustacea. 



Me'di-an (L. mediiis, middle). Refers to the 

 midline or near the middle of the bodv. 



Me-dul'la (L. inedulla, marrow). The inner 

 region of a gland or other structure in ani- 

 mals. 



Me-duI'la ob-lon-ga'ta (L., oblong medulla). 

 The most posterior of the principal divisions 

 of the vertebrate brain. 



Med'ul-la-ry plate, groove, and tube ( L. medul- 

 laris, narrow). Synonymous with neural 

 plate, groove, or tube. Three successive stages 

 in the embryonic development of the verte- 

 brate central ner\ous system. 



Med'ul-lat-ed. Used principally for certain 

 nerve fibers covered with a mvelin sheath. 



Mei-o'sis (Gr., to make smaller). See Matura- 

 tion. 



Mem'brane (L. membrana, membrane). A 

 thin, pliable sheet of cells or material se- 

 creted by cells. 



Mc-nin'ges (Gr. meninx, membrane). The 

 three membranes (dura mater, arachnoid, 

 and pia mater) covering the brain and spinal 

 cord. 



Men'to-meck-e"li-an (L. mentum, chin; after 

 J.F. Meckel, a German anatomist). Refers 

 to the anterior bones or cartilages of the 

 vertebrate lower jaw. 



Mes'en-chyme (Gr. mesos, middle; engchein, 

 to pour in ) . A loose embrvonic connective 

 tissue derived chicflv from mesoderm, al- 

 though some of its cells may have an ecto- 

 dermal or endodcrmal origin. 



Mes'en-tcr-y (Gr. mesos, middle; enteron, in- 

 testine). A thin double-walled sheet of 

 peritoneum that supports organs in the ab- 

 dominal cavity of vertebrates; also one of 



