IRR- 



157 



ISO- 



irritability (ir'itabil'itl) n. [L. irritare, 

 to provoke.] Power of receiving 

 external impressions or stimuli, and 

 reacting to them, inherent in living 

 matter (phys.). 



irritant (Ir'itant) n. [L. irritare, to 

 provoke.] An external stimulus 

 which provokes a response (phys.). 



ischiadic (is'kTad'lk) a. Ischial. 



ischial (Ts'kial) a. [Gk. ischion, a hip.] 

 Pert, or in the region of the hip ; 

 appl. artery, vein (anat.). 



ischiocapsular (Ts'kTokap'sular) a. 

 [Gk. ischion, hip ; L. capsula, little 

 chest.] Appl. a ligament joining 

 the capsular ligament and the hip 

 (anat.). 



ischiocavernous (Ts'kTokav'ernus) a. 

 [Gk. ischion, hip ; L. cavus, hollow.] 

 Appl. muscle between the hip and 

 the corpora cavernosa (anat.). 



ischiopodite (fs'kiop'odlt) n. [Gk. 

 ischion, hip ; pous, foot.] The 

 proximal joint of the walking legs 

 of certain Crustacea, or of the 

 maxillipedes (zool.). 



ischiopubic (Is'kTopu'bTk) a. [Gk. 

 ischion, hip ; L. pubis, adult.] Appl. 

 a gap or fenestra between the 

 ischium and pubis (anat.). 



ischiopubis (Ts'kTopu'bTs) n. [Gk. 

 ischion, hip ; L. pubis, adult.] The 

 ischium of Pterodactyls, the pubis 

 being excluded from the acetabu- 

 lum ; a fused ischium and pubis 



ischiorectal (Is'kTorgk'tal) a. [Gk. 

 ischion, hip ; L. rectus, straight.] 

 Pert, ischium and rectum ; appl. 

 fossa and muscles (anat.). 



ischium (Ts'kTum) n. [Gk. ischion, 

 hip.] The ventral and posterior 

 bone of each half of the pelvic 

 girdle of Mammals ; an ischiopodite 

 (zool.). 



isidiferous (I'sTdif'erus) a. [Gk. isis, 

 plant ; ~L.ferre, to bear.] Bearing 

 isidia (bot.). 



isidioid (IsTd'Toid) a. [Gk. isis, plant ; 

 cidos, like.] Like an isidium (bot.). 



isidium (IsTd'ium) ., isidia (Isid'ia) 

 plu. [Gk. isis, plant.] Coral-like 

 soredia on the surface of some 

 Lichens (bot.). 



isidophorous (I'sTdof'oriis) a. [Gk. 

 isis, plant ; pherein, to bear.] Isid- 

 iferous. 



islets of Langerhans, spherical or 

 oval bodies scattered throughout 

 the pancreas, concerned in the 

 metabolism of sugar in the body 

 (phys.). 



isobilateral symmetry, the quality 

 of leaves whose upper and lower 

 surfaces are similar (dot.). 



isocarpous (I'sokar'pus) a. [Gk. isos, 

 equal ; karpos, fruit.] Having car- 

 pels and perianth divisions equal 

 in number (bot.). 



isocercal (I'soseYkal) a. [Gk. tsos, 

 equal ; kerkos, tail.] With verte- 

 bral column ending in median line 

 of caudal fin (zool.). 



isochela (I'soke'la) n. [Gk. isos, equal ; 

 chele, claw.] A chela with two 

 parts equally developed (zool.). 



isocytic (I'sosTt'ik) a. [Gk. isos, equal ; 

 kytos, hollow.] With all cells equal 

 (biol.). 



isodactylous (I'sodak'tiliis) a. [Gk. 

 isos, equal; daktylos, finger.] Hav- 

 ing all the digits of equal size 

 (zool.). 



isodiametric (I'sodiamgt'rik) a. [Gk. 

 t'sos, equal ; dia, through ; metron, 

 measure.] With cells or other 

 structures of equal diameter (bot.). 



isodont (I'so'dont) a. [Gk. isos, equal ; 

 odous, tooth.] Having teeth all 

 equal (zool.). 



isodynamic (I'sodtnam'ik) a. [Gk. 

 isos, equal ; dynamis, power.] Of 

 equal strength ; appl. foods (phys.). 



isogamete (I'sogamet') n. [Gk. isos, 

 equal ; gamos, marriage.] One of 

 a pair of equal gametes, not 

 differentiated from one another. 



isogamous (Isog'amus) a. [Gk. isos^ 

 equal ; gamos, marriage.] Having 

 the gametes alike (hot.). 



isogamy (isog'amT) n. [Gk. isos, 

 equal ; gamos, union.] Sexual 

 union, or union of similar gametes 

 (biol.). 



isogenetic (I'sojengt'ik) a. [Gk. isos, 

 equal ; genos, offspring.] Arising 

 from the same or a similar origin 

 (biol.). 



isogenous (isoj'e'nus) a. Isogenetic. 



isognathous (Isog'nathus) a. [Gk. 

 isos, equal; gnathos, jaw.] Having 

 both jaws alike (zool.). 



isomastigote (I'somas'tTgot) a [Gk. 

 isos, equal; inastix, whip.] Having 



