EXO- 



101 



EXO- 



exochorion (Sk'sok5'rI5n) n. [Gk. 

 exo, without ; chorion, chorion.] 

 The outer layer of the membrane 

 secreted by the follicular cells 

 surrounding the egg in the ovary 

 of Insects (zoo/.). 



exocoel (Sk'sosel) n. [Gk. exo, with- 

 out ; koilos, hollow.] The space 

 between the mesenteries of ad- 

 jacent couples in certain Zoantharia 

 (goo/.). 



exocoelar (eVsose'lar) a. [Gk. exo, 

 without ; koilos, hollow.] Pert, the 

 parietal wall of the coelom ; pert. 

 space between adjacent couples 

 of mesenteries in the Zoantharia 

 (zoo/.). 



exocoelom (eVsose'lom) n. [Gk. 

 exo, without ; koilos, hollow.] The 

 extra-embryonic body cavity of the 

 embryo (emb.}. 



exoderm (eVsodgrm) n. [Gk. exo, 

 without ; derma, skin.] The dermal 

 layer of Sponges supposed by 

 Haeckel to be equal to ectoderm 

 of other animals (zoo/.). 



exodermis (eYsodeVmis) n. [Gk. 

 exo, without ; L. dermis, skin.] 

 See ectoderm. 



exogamete (Sk'sogamet') n. [Gk. 

 exo, without ; gametes, mate.] A 

 reproductive cell which fuses with 

 one derived from another source 

 (zoo/.). 



exogamy (Sksog'amT) n. [Gk. exo, 

 without ; gamos, marriage.] Con- 

 jugation or fusion of isogametes 

 with others of a different brood 

 (6to/.). 



exogastrically (ek'sogas'trikal!) adv. 

 [Gk. exo, without ; gaster, belly.] 

 Where the shell is coiled towards 

 the dorsal surface of the body 

 (zoo/.). 



exogenous (e'ksoj'e'nus) a. [Gk. exo, 

 without ; genos, race.] Developed 

 from superficial tissue, the super- 

 ficial meristem (oof.) ; growing from 

 parts which were previously ossified 

 (zoo/.). 



exognathion (6k'sognath'l8n) n. [Gk. 

 exo, without ; gnathos, jaw.] The 

 maxillary portion of the upper jaw ; 

 the maxilla with exception of 

 endognathion and mesognathion 

 (anaf.). 



exoperidium (e'k'sope'rid'ium) n. 



[Gk. exo, without ; peridion, a 

 small wallet.] The outer layer of 

 the spore case in certain Fungi 



exoplasm (eVsoplazm) n. [Gk. 

 exo, without ; plasma, something 

 moulded.] The ectoplasm (biol.). 



exopodite (gksop'odit) n. [Gk. exo, 

 without ; potts, foot.] The outer 

 branch of a typical biramous 

 crustacean limb (zool.}. 



exoskeleton (6k'sosk61'6ton) n. [Gk. 

 exo, without ; skeletos, hard.] A 

 hard supporting structure secreted 

 by the ectoderm or by the skin 

 (zoo/.). 



exosmosis (gk'sosmo'sis) n. [Gk. 

 exo, without ; osmos, impulse.] 

 The passing out through a mem- 

 brane of a gas or fluid, a phase in 

 osmosis (phys.~). 



exospore (fik'sospor) n. [Gk. exo, 

 without ; sporos, seed.] The outer 

 coating of the sporangial wall ; one 

 of the conidia (&?/.). 



exosporlum (ek'sospo'rmm) n. [Gk. 

 exo, without ; sporos, seed.] The 

 outer layer of the sporangial wall 

 (bot.}. 



exostome (eVsostom) n. [Gk. exo, 

 without ; stoma, mouth.] The 

 opening or foramen in the outer 

 wall of the ovule (bot.}. 



exostosis (eVs8sto's!s) n. [Gk. exo, 

 without ; osteon, bone.] The forma- 

 tion of knots on the surface of wood 

 (oot.) -, the formation of knob-like 

 outgrowths of bone at a damaged 

 portion, or of dental tissue in a 

 similar way (anaf.). 



exotheca (eYsothe'ka) n. [Gk. exo, 

 without ; theke, box.] The extra- 

 capsular tissue of a Coral (zoo/.). 



exothecal (gk'sothe'kal) a. [Gk. exo, 

 without ; theke, box.] Pert, tissue 

 outside the theca of a Coral (zoo/.), 



exothecate (eVsothe'kat) a. [Gk. 

 exo, without ; theke, box.] Having 

 an exotheca (zoo/.). 



exotic (gksot'ik, 6gz8t'Tk) a. [Gk. 

 exotikos, foreign.] Signifying an 

 introduced or non-endemic plant 

 (tof.). 



exotospore (Skso'tospor) n. [Gk. 

 exotikos, foreign ; sporos, seed.] A 

 sporozoite (zoo/.). 



exotropism (6ks6t'roplzm) n. [Gk. 



