XEN- 



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xenophya (zeVoffa) n.plu. [Gk. xenos, 

 strange ; phyein, to grow.] Foreign 

 bodies deposited in interspaces of 

 certain Sarcodina, or used in forma- 

 tion of shells of certain Protozoa 

 (zool.}. 



xerophilous (zerof ilus) a. [Gk. xeros, 

 dry ; philein, to love.] Able to 

 withstand drought ; appl. plants 

 adapted for a limited water supply 

 (hot.}. 



xerophyte (ze'rofit) n. [Gk. xeros, 

 dry ; phyton,- plant.] A xerophilous 

 plant ; a plant growing in desert 

 or alkaline soil (dot.). 



xiphihumeralis (zifihume'ra'lis) n. 

 [Gk. xiphos, sword ; L. humerus, 

 shoulder.] A muscle extending 

 from xiphoid cartilage to humerus 

 (anat.). 



xiphiplastron (zif'Tplas'tron) n. [Gk. 

 xiphos, sword ; F. plastron, shield.] 

 The fourth lateral plate in the 

 plastron of Chelonia (zool}. 



xiphisternum (zifisteVnum) n. [Gk. 

 xiphos, sword ; L. sternum, breast- 

 bone.] The posterior segment or 

 ensiform process of the sternum 

 (anat.'). 



xiphoid (ztf'oid) a. [Gk. xiphos, 

 sword ; eidos, shape.] Sword- 

 shaped ; ensiform (anat.}. 



xiphoid process, the last segment of 

 the sternum (anat.} ; the tail or 

 telson of Limulus (zool.}. 



xiphophyllous (zif'ofil'us, zlfof'ilus) a. 

 [Gk. xiphos, sword ; phyllon, leaf.] 

 Having sword-shaped leaves' (hot.}. 



xylem (zl'lfim) . [Gk. xylon, wood.] 

 The lignified portion of a vascular 

 bundle (bot.}. 



xylocarp (zi'lokarp) n. [Gk. xylon, 

 wood ; karpos, fruit.] A hard 

 woody fruit (bot.}. 



xylogen (zl'lojgn) n. [Gk. xylon, 

 wood; gignesthai, to produce.] The 

 forming wood in a bundle (bot.}. 



xyloid (zfloid) a. [Gk. xylon, wood ; 

 eidos, shape.] Woody, or re- 

 sembling wood in structure (dot.}. 



xyloma (zilo'ma) n. [Gk. xylon, 

 wood.] A hardened mass of 

 mycelium which gives rise to spore- 

 bearing structures in certain Fungi 

 (bot.}. 



xylophagous (zllof'agus) a. [Gk. 

 xylon, wood ; phagein, to eat.] 



Wood-eating ; appl. certain Mol- 

 luscs and Insects (zool.}. 



xylostroma (zHostro'ina) n. [Gk. 

 xylon, wood ; stroma, couch.] The 

 felt-like mycelium of certain wood- 

 destroying Fungi (bot.}. 



xylotomous (zllot'omus) a. [Gk. xylon, 

 wood ; temnein, to cut.] Able to 

 bore or cut wood (zool.}. 



yellow cartilage, a cartilage in 

 which the matrix is everywhere 

 pervaded by yellow connective 

 tissue fibres (anat.}. 



yellow cells, cells surrounding the 

 gut of an earthworm, probably ex- 

 cretory in function ; cells occurring 

 in the intestine of Turbellarians ; in 

 Radiolarians, symbiotic algae or 

 zoochlorellae (zool.}. 



yellow fibres, see elastic fibres. 



yellow spot, the macula lutea of the 

 retina (anat.}. 



yolk (yok) n. [A.S. geoloca, the 

 yellow part] The inert, or non- 

 formative, nutrient material in the 

 ovum (emb.}. 



yolk-duct, the vitelline duct (zool.}. 



yolk - epithelium, the epithelium 

 surrounding the yolk-sac (emb.}. 



yolk-gland, a gland in connection 

 with the reproductive system in 

 certain worms by which the egg is 

 furnished with a supply of food- 

 material ; the oviducal gland in 

 certain vertebrates (zool}. 



yolk-nucleus, a cytoplasmic body 

 appearing in the ovarian egg (cyt.}. 



yolk-plates, parallel lamellae into 

 which the deutoplasm may be split 

 up in egg-yolk of Amphibia and 

 many Fishes. 



yolk -plug, the mass of yolk-cells 

 filling up the blastopore, as in the 

 Frog (cyt}. 



yolk-pyramids, certain of the cells 

 formed in the segmenting egg of 

 the Crayfish (zool.}. 



yolk-sac, a membranous sac at- 

 tached to the embryo and contain- 

 ing yolk, which passes to the 

 intestine through the vitelline duct, 

 and acts as food for the developing 

 embryo (emb.}. 



