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or towards the axis ; of anthers, 

 opening on the side next the 

 pistil (60 f.). 



Introvert (m'trovert) n. [L. intro, 

 within ; vertere, to turn.] That 

 which is capable of involution, as 

 the anterior region of the body of 

 certain zooids, of certain Annulates, 

 the mouth extremity of certain 

 Molluscs (zool.} ; v. to turn, bend, 

 or draw inwards (biol.). 



Intussusception (m'tussusgp'shun) n. 

 [L. intus, within ; suscipere, to 

 receive.] Growth in surface-extent 

 or volume by intercalation of par- 

 ticles among those already present 

 (biol.). 



inulase (in'ulas) n. [L. inula, the 

 plant elecampane.] A ferment of 

 plants which acts on inulin (bat.). 



inulin (m'ulin) n. [L. inula, the plant 

 elecampane.] A form of starch 

 found in plant-cell sap (bot.). 



invaginate (mvaj'inat) v. [L. in, 

 into ; vagina, sheath.] To involute 

 or draw into a sheath ; appl. the 

 insinking of a wall of a cavity or 

 vessel apparently reducing the 

 original cavity and leaving a new 

 cavity or groove visible on the 

 exterior {zool., bot.). 



invagination (invaj'ina'shun) n. [L. in, 

 into ; vagina, sheath.] Involution ; 

 introversion ; gastrula-formation by 

 infolding of the blastula wall (zool.}. 



invertase (inveVtas) n. [L. invertere, 

 to turn into.] A ferment of plants 

 which acts on cane sugar (bot.). 



invertebrate (invgr'tgbrat) a. [L. in, 

 not ; vertebra, joint.] Back-bone- 

 less ; without spinal column. 



investing bones, membrane bones. 



investment (mv&st'ment) n. [L. in, 

 in ; vestire, to clothe.] The outer 

 covering of a part, organ, animal, 

 or plant. 



involucel (invol'use'l) n. [Dim. of L. 

 involucrum, covering.] The small 

 bracts at the base of a secondary 

 umbel ; a partial involucre (hot.}. 



involucellate (Invol'usSl'at) a. [Dim. 

 of L. involucrum, covering.] Bear- 

 ing involucels (bot.). 



involucral (in'volu'kral) a. [L. in- 

 volucrum, covering.] Pert, or like 

 an involucre (bot.). 



involucrate (m'volu'krat) a. [L. in- 



volucrum, covering.] Bearing in- 

 volucres (bot.). 



involucre (in'volu'ker) n. [L. invo- 

 lucrum, covering.] Bracts at the 

 base of chief branches of compound 

 umbels (bot.). 



involucrum (in'volu'krum) n. [L. 

 involucrum, covering.] In Hydro- 

 medusae, the protective cup into 

 which nematocysts can be spirally 

 retracted ; the metanotum of Or- 

 thoptera (zool.) ; an involucre (hot.). 



involuntary (invol'untarl) a. [L. in, 

 not ; voluntas, a wish.] Not under 

 control of the will ; appl. certain 

 plain unstriped muscles, as of the 

 alimentary canal, and to their 

 movements (phys.). 



involute (in'volut) a. [L. involutus, 

 rolled up.] Of leaves, having the 

 edges rolled inwards at each side 

 (bot.) ; of shells, closely coiled 

 (zool.). 



involution (in'volu'shun) n. [L. in- 

 volvere, to roll up.] Appl. forms 

 that have become deformed in 

 structure owing to unfavourable 

 conditions, but not to such an 

 extent as to be incapable of re- 

 covery if the conditions improve ; 

 as the so-called "latent bodies" in 

 the Haemoflagellate life - history 

 (zool.). 



iodothyrin (lo'dothl'nn) n. [Gk. iodes, 

 violet ; thyreos, shield.] An iodine 

 compound in the colloid material 

 of the thyroid gland (phys.). 



iridial angle, the filtration angle of 

 the eye ; an angular recess at the 

 anterior surface of the attached 

 margin of the eye (anat.). 



iridocytes (ir'idoslts) n. plu. [L. iris, 

 rainbow; Gk. kytos, hollow.] Guanin 

 granules, bodies or plates, of which 

 the reflecting tissue of the skin of 

 Fishes is composed ; iridescent 

 cells in the integument of Sepia 

 (zool.). 



iridomotor (ir'idomo'tor) a. [L. iris, 

 rainbow ; movere, to move.] Con- 

 nected with the movements of the 

 iris (phys.). 



iris (I'ris) n. [L. iris, rainbow.] A 

 thin, circular, contractile disc sus- 

 pended in the aqueous humour of 

 the eye between the cornea and 

 lens (anat.). 



