Volutin 



Zymologiit 



chromatin substance in Spirillum 

 volutana Ehrenb. (Minchin). 



Wa'ter-con'tent, the amount held in 

 tissue or soil ; ~ Loss, amoiant 

 removed by some natural event 

 or artificial operation. 



Welwitschie'tam, an association of 

 Wdwitschia Hook f . 



Wiesner's Law, refers to leaf»position 

 with regard to light for maximum 

 illumination. 



wcr'king, an expression for " breaking 

 of the meres," as of Oscillatoria 

 prolifica Gomont in a lake in New 

 York Botanic Garden. 



X chromosome, one which conveys 

 the quality of sex. 



Xenautog'amy {+ Autogamy), with 

 homogamous flowers, favouring 

 cross-pollination, but self-fertile 

 under adverse conditions (Robert- 

 son) ; Xe'niophyte {<f>vT6v, a plant), 

 the endosperm of Angiosperms, 

 constituting a third generation 

 hitherto overlooked, now sporo- 

 phyte, gametophyte and xenophyte 

 (Trelease) ; Xenodoch'ae pi. (80x77, 

 succession), Coseres and Cliseres ; 

 anomalous successions (Gams). 



Xer'arch (dpx'?» beginning), succession 

 originating in a dry area (Cooper) ; 

 Xerocleistog'amy ( + Cleistoqamy), 

 pollination in closed flowers on 

 account of dryness (Hansgirg) ; 

 Xer'ocline {kXIvw, to recline), a 

 dry, warm slope (Clements) ; Xero- 

 dry'miam (Spviios, coppice), dry 

 thicket ; cf. Durisilvae ; Xeroge'o- 

 phytes (-fGEOPHYTE), plants whose 

 rest period is in dry periods (Mas- 

 sart) ; Xer'oid Ar'eas, pre-Devonian 

 algal climax (Clements) ; Xero- 

 phor'bium {(f>oppds, feeding), tundra, 

 dunes (Diels) ; Xeropoi'um (+ 

 Poium), steppes . (Diels) ; in a 

 dry area (Cooper) ; Xer'osere (-}- 

 Sere), a succession with reference 

 to the scanty water- content of 

 the bare area ; its subsidiary seres 

 are Lithoseres and Psammoseres 

 (Gams) ; xerotrop'ic {TpoTrq, a 

 turning), reaction towards a dry 



succession (Clements) ; xerotac'tic 

 (raKTiKos, fit for order), applied to 

 successions not greatly changing 

 {id.); Xylopod'ium ~, pi. -ia, 

 add, (2) more or less stony, hard, 

 tuberous thickening of the roots 

 and underground parts of shrubs in 

 Brazil in the steppe regions (Lind- 

 man). 



Zeu'xis (l^u^is, a joining), Frost's ex- 

 pression for chromosomal heredity. 



Zo'id, applied also to a zoospore or 

 swarm-spore (Church) ; zoidogam'ic 

 {ydfios, marriage), fertilized by 

 zoids (Wieland) ; Zoidog'amy 

 (ydi-to^, marriage), fertilization by 

 antherozoids ; Zoid'iospore ( + 

 Spore), plants whose seeds are 

 dispersed by animals (Clements) ; 

 Zona'tion, a5d, (3) separation of the 

 ooplasm from the periplasm in 

 Phytophihora De Bary (Murphy) ; 

 Zoochloreriae, pL, a symbiotic 

 form of Chlorella Beyer., associated 

 with infusoria (West) ; zooch'orous 

 (xcopeoj, I retire), distributed by 

 animals (Riibel) ; Zoogonidang'ium 

 (-f Gonidangium), an organ contain- 

 ing zoogonidia, said to be (a) 

 fun'nel ~', always terminal; (b) 

 ses'sile ~, discharging from side 

 or terminal; (c) stalked ~, from 

 side or end ; {d) ter'minal ~, from its 

 apical cell (Brand) ; Zooxantheriae, 

 pi., holophytic flagellates containing 

 a yellow pigment. 



Zygneme'tum, an association of 

 Zygnema Ag. 



Zygogen'esis (yeVeais, origin), derived 

 from sexual imion ; adj. zygogen'ic; 

 Zygone'ma {vfj /J-a, a thread), when 

 at the role of a nucleus the lepto- 

 tene threads fuse in pairs (Agar) ; 

 adj. zy'gotene ; ZygO-pachyne'ma 

 (-f Pachynema), the transitional 

 condition of the meiotic nucleus 

 in which heavy pachytene threads 

 are fusing side by side to form a 

 zygoma. 



zygop'terid, zygopteride'an, relating 

 to the fossil genus Zygopteris Corda, 



Zymorogist, a student of the course 

 of fermentation (Harshberger). 



473 



