GLOSSARY 389 



Metamerism (rne tarn' eriz'm). The condition of being divided into a number of 

 similar metameres or somites. 



Metamorphosis (met' a mor' fo sis). The transformation of a larva into an adult. 



Metaphase (met' a faze). That stage of cell division in which the chromosomes split. 



Metargiope (met' arji' o pee). A genus of spiders. 



Metatarsal (met' a tar' sal). One of the bones forming the body of the (hind) foot of 

 vertebrates. 



Metazoon (met' azo' on). An animal composed of many cells. Although the term 

 contrasts an animal with the Protozoa, it is not a name of any taxonomic group 

 of animals. 



Methyl -green (meth' il green'). A green substance used as a nuclear stain. 



Metridium (me trid' i um). A genus of sea-anemones, of the phylum Ccelenterata. 



Miastor (mi as' ter). A genus of flies; the larvae are psedogenetic. 



Microgamete (mi' kro gam' eet). The smaller one of two kinds of gametes in species 

 in which these cells differ in size. 



Micronucleus (mi' kro nu' kle us). The smaller nucleus in a cell or organism having 

 two nuclei of unequal size. 



Microstomum (mi kros' to mum). A genus of flatworms (Platj-^helminthes) of the 

 order Rhabdocoelida. 



Mid-piece (mid' pees). A minute structure in a spermatozoon, between the head and 

 the base of the tail. 



Mimic (mini' ik). An animal which resembles another animal having some repellent 

 or dangerous property which protects it. 



Mimicry (mini' ik ri). The resemblance of one species to another, especially resem- 

 blance to one having some repellent or dangerous property. 



Miocene (mi' o seen). Belonging to middle Tertiary time; succeeding the Oligocene. 



Miracidium (meer' a sid' i um). The larval form of a trematode worn such as the 

 liver fluke which enters a snail as host. 



Miranda (mi ran' da). A genus of spiders. 



Mitosis (mi to' sis). Cell division involving the formation of chromosomes, spindle- 

 fibers, etc. Also called karyokinesis. 



Model (mod' el). An animal with some protective propert.y that is repellent or 

 dangerous, to which another animal without such protective trait bears a 

 resemblance. 



Modiola (mo di' o la). A genus of marine clams. 



Moeritherium (me' ri the' ri um). An extinct animal from the Eocene of Egypt, 

 probably an early ancestor of the elephants. 



Mohl, Hugo von (mole). German botanist, 1805-1872. 



Molar {mo' ler). One of the grinding teeth of a mammal, back of the incisors and 

 canines. 



Mold (mold). A cavity in a rock representing the form of an animal or plant or other 

 object whose remains formerly occupied the cavity. 



Molecule (moV e kule). Usually a group of atoms behaving as a unit of the substance 

 which they compose. It is the smallest particle which possesses the chemical 

 nature of the substance. 



Mollusca (7nol lus' ka). The phylum of animals including the clams, snails, cuttle- 

 fishes, etc. For definition see Chapter XII. 



