YOL- 



361 



ZON- 



yolk - spherules, the remains of 

 neighbouring cells or of pseudo- 

 cells found in the ovum (smb.}. 



yolk-stalk, a short stalk or strand 

 containing ducts and connecting 

 the yolk-sac and the embryo (emb.). 



ypsilifonn (ipsil'iform) a. [Gk. T, 

 upsilon; L. forma, shape.] T- 

 shaped ; appl. the germinal spot 

 at a certain stage in its development 

 (emb.\ 



ypsilold (ip'siloid) a. [Gk. T, upsilon ; 

 eidos, resemblance.] Ypsiliform. 



ypsiloid cartilage, attached to the 

 pubes in Salamanders with func- 

 tional lungs (zoo/.). 



zalambdodont (zalam'dodont) a. [Gk. 

 za, very ; lambda, A ; odous, tooth.] 

 Appl. insectivores with narrow 

 molar teeth with V-shaped trans- 

 verse ridges (zoo/.). 



zero (ze'ro) n. [Ar. $ifrun, cipher.] 

 The origin of graduation. 



zero, physiological, the point of 

 adaptation to temperature. 



Zinn, zonule of, see zonula ciliaris 

 (anat.). 



zoaea (zoe'a) n. [Gk. zoe, life.] A 

 zoea. 



zoarium (zoa'rium) n. [Gk. zoon, 

 animal.] The whole of the indi- 

 viduals of a polyzoan colony ; a 

 polypary (zoo!.). 



zodiophilous (zo'diof'ilus) a. [Gk. 

 zoon, animal ; philein, to love.] 

 Zoophilous. 



zoea (zoe'a) n. [Gk. zoe, life.] An 

 early larval form of certain decapod 

 Crustaceans (zoo/.). 



zoeaform (zoe'aform) a. [Gk. zoe, 

 life ; L. forma, shape.] Shaped 

 like a zoea (zoo/.). 



zoecial (zoe'shial) a. [Gk. zoon, 

 animal ; oikos, house.] Pert, or 

 resembling a zooecium (zoo/.). 



zoecium (zoe'shtum) n. [Gk. zoon, 

 animal ; oikos, house.] See zooe- 

 cium. 



zoetic (zoet'ik) a. [Gk. zoe, life.] Of 

 or pert, life (biol.). 



zoic (zo'lk) a. [Gk. zoikos, peri, life.] 

 Pert, animals or animal life (zoo/.). 



zoid (zoid) a. [Gk. zoon, animal ; 

 eidos, resemblance.] A sporozoite 

 formed by division of sporoblasts 

 of Haemosporidia (zoo/.). 



zoidophore (zo'Idofor) n. [Gk. zoon, 

 animal ; eidos, shape ; pherein, to 

 bear.] A spore mother cell or 

 sporoblast formed by the segmenta- 

 tion of the oocyte in Haemosporidia 

 (zoo/.). 



zona (zo'na) n. [Gk. zone, girdle.] 

 A zone, band, or area. 



zona arcuata, the inner part of the 

 basilar membrane supporting the 

 organ of Corti (anat.). 



zona fasciculata, radially arranged 

 columnar cells in the suprarenal 

 gland below the outer layer (anat.). 



zona pectinata, the outer division of 

 the basilar membrane (anat.). 



zona pellucida, the thick transparent 

 membrane surrounding the mam- 

 malian ovum (smb.). 



zona reticularis, the inner cortical 

 layer of the suprarenal gland 

 (anat.). 



zonal (zo'nal) a. [L. zonalis, pert. 

 zone.] Of m pert, a zone. 



zonal symmetry, see metamerism 

 (zoo/.). 



zonal view, the view of a Diatom in 

 which the girdle is seen (bot.). 



zonary (zo'nari) a. [Gk. zonarion, 

 dim. of zone, girdle.] Pert, the 

 Zonaria, a division of deciduate 

 Mammals in Huxley's classification 

 (zoo/.). 



zonary placenta, see placenta. 



zonate (zo'nat) a. [Gk. zone, girdle.] 

 Zoned or marked with rings ; ar- 

 ranged in a single row, as various 

 tetraspores (bot.}. 



zone (zon) n. [Gk. zone, girdle.] 

 An area Characterized by a similar 

 fauna or^flora (biol.) ; a stratum or 

 set of beds characterized by a 

 typical fossil or set of fossils (pal.). 



zonociliate (zo'nosU'fat) a. [Gk. zone, 

 girdle; L. ciliunt, eyelash.] Banded 

 with cilia, as certain annelid larvae 

 (zoo/.). 



zonoid (zo'noid) a. [Gk. zone, girdle ; 

 eidos, resemblance.] Like a zone. 



zonolimnetic (zo'nolimnet'ik) a. [Gk. 

 zone, girdle ; limne, pool.] Of or 

 pert, a certain zone in depth ; appl. 

 plankton (biol.). 



