378 PRINCIPLED OF ANIMAL BIOLOGY 



Erythrodextrin (er' i thro deks' trin). A carbohydrate obtained by hj'^drolysis of 

 stare !i. 



Erythrosin (c riih' ro sin). A red substance used as a protoplasmic stain. 



Esophagus (e sof a gus). In tlic earthworm, a narrow passage leading from the 

 pharynx to the crop. In vertebrates, the passage between the pharynx and the 

 stomach. 



Eudorina elegans (u' do ri' na eV e gam). A species of colonial chlorophyll-bearing 

 organism whose cells are imbedded in a spherical jelly-like mass. 



Euglena (u gle' na). A genus of green flagellate Protozoa. 



Euglypha {u glif a). A genus of rhizopod Protozoa, of the order Foraminifera. 



Euplectella {u' plek teV la). A genus of siliceous sponges. 



Eustachian tube {u sta' ki an tube'). A passage between the pharynx and the tym- 

 panum or middle ear. 



Eutheria (« the' ri a). A subclass of Mammalia comprising the viviparous mammals. 



Eutrephoceras {u' trefos' er as). A genus of extinct cephalopods resembling Nautilus. 



Evagination (e vaj' i na' shun). The folding of a layer of cells outward from an en- 

 closed cavit}\ 



Evolution (ev' o lu' shun). The gradual or sudden change of, animals or plants through 

 successive generations. 



Evolve (e volv'). To change ; to undergo evolution. 



Excretion {eks kre' shun). The elimination of waste substances. As a noun, a sub- 

 stance excreted. 



Exhalent {eks ha' lent) . Breathing out; applied to one of the siphons of a clam 

 or mussel. 



Exoskeleton (eks' o skeV e tun) . A skeleton on the outside of the body, as in the 

 arthropods. 



External respiration {eks ter' nal res' pi ra' shun). The passage of oxygen from the 

 surrounding air or water to the blood. 



Ex-umbrella {eks' um breV la). The convex side of a medusa. 



Fi {ef wun'). An individual or generation of individuals resulting from the crossing 



of two unlike parents. An abbreviation of the words first filial. 

 F2 {ef too'). An individual or generation of individuals resulting from the mating of 



two Fi individuals as parents. An abbreviation of the words second filial. 

 F3 {ef three'). An individual or generation of individuals whose parents are F2 



individuals from a previous cross. 

 Factor {fak'ter). Something in a germ cell or other cell which is responsible for a 



hereditary characteristic. Also called gene. In a general sense, factor means any 



agent or cause of any phenomenon. 

 Family (Jam' Hi). A taxonomic group of higher rank than the genus but below the 



order. 



Fasciola hepatica {fas si' o la he pat' i ka). A species of parasitic flatworm (Trema- 



toda), commonly called the liver fluke. 

 Fat (fat). A compound of glycerol and one or more fatty acids. 

 Fauna {faw' na). Collectively, the animals of a given region or of a given period of 



time. 

 Femur {fe' mur). The single bone of the thigh in vertebrates above the fishes. 

 Feral {fe' ral). Escaped from domestication. Also, sometimes, wild. 



