910 TEXTBOOK OF ZOOLOGY 



Entomology (en'to mol 6 jl), the branch of zoology that deals with the study 



of insects. 

 Entozoic (en'to zo'ik), forms which live within the bodies of other animals. 

 Enzymes (en'zimz), substances that bring about chemical transformation. 

 Ephyra (ef'i ra), the free-swimming larval form of the Scyphozoa. 

 Epiboly (epib'61i), posterior growth of a fold of the blastoderm over the 



surface of an embryo in the formation of the enterou during gastrula- 



tion. 

 Eplgenesis (ep i jen'e sis), the conception that the parts of the organism arise 



from an undifPerentiated germ cell. 

 Epithelium (ep'i the li um), a sheet of cells covering an internal or external 



surface of the body. 

 Equatorial (e kwa to'ri al) plate, the platelike arrangement of chromosomes 



lying in the plane of the equator of the mitotic spindle during cell 



division. 

 Erepsin (erep'sin), an intestinal enzyme which splits peptones into amino 



acids. 

 Estivation (es ti va'shun), a dormant condition adopted by certain animals 



during summer. 

 Eugenics (ujen'iks), the science of genetics applied to human kind, usually 



for the purpose of improvement. 

 Euglenoid (u gle'noid), resembling a Euglena, as euglenoid movement. 

 Eustachian (usta'kian) tube, the tube extending from the middle ear to 



the pharynx. 

 Evagination (e vaj'i na'shun), the unequal growth outward of a surface layer, 



one of the processes by which differentiation of organs is produced. 

 Eviscerate (evis'erat), to remove or cast out the internal organs. 

 Exopodite (eks op'o dit), the external branch of the appendages. 

 Exoskeleton (ek so skel'e tun), the hardened parts of the external integu- 

 ment of an animal. , 

 Expire (ekspir'), to expel water or air in the process of respiration. j 



Factor (fak'ter), one of several interacting elements in a complex process. 

 Agency influencing the development of an individual, as those carried 

 in the genes of chromosomes. 



Fauna (fo'na), a term referring to animal life. 



Feces (fe'sez), the indigestible portion of the food which passes through 

 the alimentary canal and is discharged by way of the anus. 



Fertilization (fur ti li za'shun), the union of a mature ovum and a mature 

 spermatozoon to produce a zygote. 



Fetus (fe'tus), an advanced stage of the embrj-o of a mammal before birth. 



Fibrin (fi'brin), the fibrous material in a blood clot; formed when fibrinogen 

 of the blood is exposed to air. 



Filtrahle virus (fil'trab'l vi'rus), an organism too small to be seen with the 

 microscope and usually within cells of other organisms. 



First filial (f first fil'ial), generation, the individuals arising from a particu- 

 lar mating. 



Fission (fish'un), division of an organism into approximately equal parts. 



Flagellum (flajel'iim), a whiplike locomotor structure of a cell or single- 

 celled animal. 



Follicle (fol'ik'l), a cellular sac or pocket. 



Fragmentation (frag men ta'shun), a process by which individuals of certain 

 Protozoa and simple Metazoa may divide internally to form several new 

 individuals. 



Freemartin (fre'martin), a modified female member of a pair of cattle twins 

 which shows certain male features. 



