844 Appendix 



Mold (A.S. molde, earthy), saprophytic fungi. 



Molecule (mol'ekul) (L. moles, mass), an aggregate of two or more atoms com- 

 bined chemically. 



Mollusca (mol-lus'ka) (L. mollis, soft), soft-bodied animals such as clams, 

 snails, etc. 



Molt (L. muture, to change), shedding of an outer covering. 



Monecious (mo -ne' shus) (Gr. monos, one; oikos, household), both male and 

 female reproductive organs in the same individual (same as hermaphro- 

 ditic; contrast with Diecious). 



Monohybrid (mon o -hi' brid) (Gr. monos, single; L. hybrida, mongrel), offspring 

 from parents who differ in one trait. 



Monozygotic (mon o zi -got' ik) (Gr. monos, one; zeugon, yoke), two or more off- 

 spring formed from one zygote (fertilized egg). 



Morphogenesis (mor fo -jen' e sis) (Gr. morphe, form; genesis, origin), origin and 

 development of form and structure in an organism. 



Morphology (mor -fol' o ji) (Gr. morphe, form; logos, study), dealing with form 

 and structure of animals and plants. 



Morula (mor' u la) (L. morum, berry), mass of cells, called blastomeres, formed 

 by cleavage of the egg in early development of many animals. 



Motor fibers (L. moveo, move), nerve fibers whose impulses cause movement (in 

 muscles). 



Mucous membrane (mu' kus) (L. mucus, slime), lining of alimentary tract and 

 respiratory system. 



Multiple^ factors, two or more pairs of genes which have a similar or cumulative 

 effect. 



Mutation (mu -ta' shun) (L. mutare, change) an abrupt inheritable germinal 

 variation. 



Mutual symbionts (sim'bionts) (Gr. sym, with; bios, life), living together for 

 mutual benefit. 



Mycelium (mi-se'lium) (Gr. mykes, mushroom), mass of filamentous hyphae of 

 all true fungi. 



Myoblast (mi' o blast) (Gr. myo, muscle; blastos, bud), muscle-developing cell. 



Myogenic theory (mi o -jen' ik) (Gr. myo, muscle; gene, origin), theory that the 

 rhythmic heartbeat is due to innate properties of heart muscles rather than 

 nerve impulses. 



Myoneme (mi'onem) (Gr. friyo, muscle; nema, thread), contractile fiber of cer- 

 tain protozoa. 



Myosin (mi' o sin) (Gr. myo, muscle), protein of muscle. 



Myotome (mi'otom) (Gr. ?7iyo, muscle; tome, cut), muscle segments of the body 

 wall of embryonic higher chordates and of adult lower chordates. 



Myxomycophyta (mix o my -kof i ta) (Gr. myxos, slime; mykos, fungus, phyta, 

 plants), the phylum of plants including slime molds. 



Myxamoeba (miks a -me' ba) (Gr. myxa, slime; amoeba, change), swarm cell of 

 slime mold. 



N 



Nacreous (na'kreus) (L. nivcr^, mother-of-pearl), pearly. 

 Nares (na' res) (L. nare) , nost)ils. 



Natural selection, Darwin's theory that the fittest individuals survive through 

 natural processes of struggle. 



