DIS- 



79 



DIS- 



tiiskos, disc ; blastos, bud.] A 

 blastula formed from a meroblastic 



eg 



with disc-like blastoderm 



discocarp (dis'kokarp) n. [Gk. diskos, 

 disc ; karpos, fruit.] A special 

 enlargement of the thalamus below 

 the calyx (bot.). 



dlscoctasters (dis'koktas'terz) n. plu. 

 [Gk. diskos, disc ; okto, eight ; 

 aster, star.] Sponge spicules with 

 eight rays terminating in discs, 

 each disc corresponding in position 

 to the corners of a cube ; a modi- 

 fied hexactine (zoo/.). 



disced actylous (dis'kodak'tilus) a. 

 [Gk. diskos, disc ; daktylos, finger.] 

 With suckers at the ends of the 

 fingers (zoo/.). 



discohexactine (dis'kohgksak'tin) n. 

 [Gk. diskos, disc ; hex, six ; actis, 

 ray.] A sponge spicule with six 

 equal rays meeting at right angles 

 (zoo!.). 



discohexaster (dis'kdhgksas'ter) n. 

 [Gk. diskos, disc ; hex, six ; aster, 

 star.] A hexactine with the rays 

 ending in discs (zoo/.). 



discoid (dis'koid) a. [Gk. diskos, 

 disc ; eidos, resemblance.] Flat 

 and circular ; disc-shaped. 



discoidal (dlskoi'dal) a. [Gk. diskos, 

 disc ; eidos, like.] Disc-like ; appl. 

 segmentation in which the blasto- 

 derm forms a one-layered disc or cap 

 which spreads over the yolk (emo.). 



discontinuous variation, see muta- 

 tion. 



disconula (diskon'ula) n. [Gk. diskos, 

 disc.] An eight-rayed stage in the 

 larval development of certain 

 Coelenterates (zoo/.). 



discooctaster (dis'kooktas'ter), see 

 discoctasters. 



discoplacenta (dis'koplasen'ta) ;;. [Gk. 

 diskos, disc ; L. placenta, placenta.] 

 A placenta with the villi on a 

 circular cake-like disc (zoo/.). 



discus proligerus, in a Graafian 

 follicle, the mass of cells immedi- 

 ately surrounding the ovum (emb.). 



disjunct (disjungkt') a. [L. dis, apart ; 

 jungere, to join.] Having the body 

 regions separated by deep con- 

 strictions (zoo/.). 



disjunctive symbiosis, a mutually 

 helpful condition of symbiosis 



although there is no direct con- 

 nection between the partners (oio/.). 



disk, see disc. 



dispermous (dispeYmus) a. [Gk. dis, 

 twice ; sperma, seed.] Having two 

 seeds (oof.). 



dispenny (dlspeYm!) n. [Gk. dis, 

 twice ; sperma, seed.] The entrance 

 of two spermatozoa into an ovum 

 (biol.). 



dispersal (dispeYsal) n. [L. dis, 

 apart ; spargere, to strew.] The 

 actual scattering or distributing of 

 organisms on the earth's surface 



(fflO/.). 



dispireme (dlspfrem) n. [Gk. dis, 

 twice ; speirema, skein.] The stage 

 of karyokinests in which each 

 daughter nucleus has given rise to 

 a spireme (cyt.). 



displacement (displas'mSnt) n. [O.F. 

 desplacier, to displace.] An abnor- 

 mal position of any part of a plant 

 due to its shifting from its normal 

 place of insertion (bot.\ 



dissected (disgk'ted) a. [L. dis, apart ; 

 secure, to cut.] Having the lamina 

 cut into lobes, the incisions reaching 

 nearly to the midrib (eot.). 



dissepiment (disSp'iment) n. [L. dis, 

 apart ; saepire, to hedge in.] The 

 partition found in some compound 

 ovaries (bot.) in Corals, one of 

 the oblique calcareous partitions 

 stretching from septum to septum 

 and closing the interseptal loculi 

 below (zoo/.). 



dissilient (dlsil'ien t) a. [L. dis, apart ; 

 salire, to leap.] Springing open ; 

 appl. capsules of various plants 

 which dehisce explosively (bot.). 



dissoconch (dis'okongk') n. [Gk. 

 dtssos, double ; kongche, shell.] The 

 shell of a veliger larva (zoo/.). 



dissogeny (disoj'gni) n. [Gk. dissos, 

 double ; genos, birth.] The con- 

 dition of having two sexually mature 

 periods in the same animal one in 

 the larva, one in the adult (zoo/.). 



dissogony (disog'oni), see dissogeny. 



distal (dis'tal) a. [L. dis, apart ; stare, 

 to stand.] Standing far apart, appl. 

 bristles, etc. ; pert, end of any 

 structure farthest from the middle 

 line of the organism (oio/.). 



distichalia (dlstlka'lla) n. plu. [Gk. 

 distichos, with two rows.] In 



