GLOSSARY 597 



hydrostatic (hi dr6 stat' Ik). A term applied to an organ which regulates the specific 

 gravity of an aquatic animal, like a fish, in relation to that of water. 



hyp- (hip). G.; under, less. 



hyper- (hi' per). G.; above, beyond, over. 



hypermetamorphosis (hi per m6t a mor' fo sis). A metamorphosis in insects involving 

 more than the stages of egg, larva, pupa, and adult. 



hypodermis (hi p6 dur' mis). A layer of epithelial cells under a superficial cuticula. 



hypostome (hi' p6 stom). A conical projection in coelenterates at the tip of which is 

 the mouth. 



Identical twins. Twins which are alike and which presumably come from a single 



egg cell, 

 ileum (ir eiim). The last and longest of three divisions of the small mtestine of 



mammals. 

 ilium (ir I um). The dorsal bone of the pelvis in Amphibia and higher vertebrates; 



adj., iliac, 

 imago (I ma' go). The adult of insects; adj., imaginal (I mftj' I nftl). 

 immunity (I mu' nl tl). The absence of susceptibility to disease. 

 inbreeding. The production of young by two closely related individuals, 

 individuality. That which belongs to one individual organism as distinct from all 



others. 

 ingestion (In j6st' chun). The taking of food into the digestive cavity and its prepa- 

 ration for digestion. 

 inhalation (In ha la' shtin). The taking of air into the lungs, 

 inhibit (In hib' It). To check or restrain. 

 insectivorous (In s6k tlv' 6 riis). Insect-eating; an insect-eating animal is known as 



an insectivore (In s6k' tl vor). 

 inspiration (In spl ra' shun). The taking of oxygen into an animal organism; or 



its passage from the blood into the tissues. 

 instar (In' star). A period between molts in an insect larva, 

 instinct (In' stinkt). A mode of action determined by an inherited action pattern 



which under appropriate conditions and when brought into play by the proper 



stimulus causes a series of associated reflex acts leading to a definite end; adj., 



instinctive (In stink' tlv). 

 integration (in te gra' shun). The development of unity in an organism, 

 intelligence. A mode of action freely modified by previous experience, 

 inter- (In' ter). L.; between, among, 

 intercellular. Between cells. 

 internal secretion. A secretion passed into the blood instead of into the lumen of a 



gland or out upon a surface. 

 interoceptor (In ter 6 s6p' tor). A sense organ stimulated by some agent from within 



the body. 

 intestine (In t6s' tin). That part of the alimentary canal in which absorption takes 



place; in mammals it is divided into the small and the large intestine; adj., 



intestinal, 

 intra- (in' tra). L.; within, 

 intracellular. Within a cell. 

 intussusception (In tiis su s6p' shtin). The introduction of new particles between 



those already related in a mass. 

 invagination (In vSj Ina'shun). The infolding of a sheet of cells or membrane to 



form a cavity. 

 ion (i' 6n). A free atom or radical in a solution, which bears an electrical charge, 

 irritability. The capacity to respond to a stimulus. 



