GLOSSARY 



331 



metamere, mefa mer (Gr. meta, after ; meros, a part), one of a longitudinal 



series of parts which are serially homologous with one another, 

 metamorphosis, meta mor'fo sis (Gr. mefa, change ; morphe, shape), a 



marked change in form or function. 

 metaphase, mettafdz (Gr. mefa, after), the middle stage of mitosis during 



which occurs the splitting of the chromosomes in the equatorial plate. 

 metaplasm, met'aplazm (Gr. meta, after; plasma, a thing formed), applied 



to lifeless inclusions in protoplasm. 



Metazoa, metazo'a (Gr. meta, after; zoon, an animal), many-celled ani- 

 mals. 

 microgamete, mlkrogam'et (Gr. mikros, small ; gamete, a wife), a small 



reproductive cell, the spermatozoon. 

 micromere, mi'kromer (Gr. mikros, small; meros, a part), the smaller cells 



in the embryonic stages of certain animals, 

 micronucleus, ml krd nu'kle us (Gr. mikros, small ; nucleus}, the smaller of 



two nuclei in certain Protozoa. 



mitosis, mi to' sis (Gr. mitos, a thread), indirect nuclear division, 

 monoecious, mo ne'shus (Gr. monos, one ; oikos, a house), having both male 



and female sexual organs. 

 morphology, mbrfol'oji (Gr. morphe, form; logos, description), the science 



of form and structure. 

 moult, molt (L. mutare, change), the process of casting off tegumentary, 



cuticular, or exoskeletal st-.uctures. 

 mutation, mu td'shon (L. mutare, change), a theory of the origin of species 



(see p. 295). 



nematocyst, nem'atosist (Gr. nema, thread; kustis, a bag), a structure con- 

 taining a thread, characteristic of coelenterates. 



nephridium, nefricfium (Gr. nephros, a kidney), one of the excretory 

 organs of the earthworm. 



neuron, nii'ron (Gr. neuron, a nerve), a nerve cell with all its prolongations. 



nucleolus, nukle'd lus (L. nucletts, a small nut), a deeply staining body often 

 present within a nucleus. 



nucleus, nt't'kleus (L. nucleus, a small nut), the dynamic center of a cell. 



nutriment, nu'triment (L. nutrire, nourish), that which promotes the 

 growth or repairs the waste of animal bodies. 



nutrition, nutrish'on (L. nutrire, nourish), the processes by which organ- 

 isms take in food and add it to their living tissues. 



ocellus, osel'us (L. ocellus, a little eye), a simple eye of an insect. 

 oesophagus, e sofa gus (Gr. oisophagos, the gullet), the canal through which 

 food and drink passes to the stomach. 



