226 KIXHIKKCIIKS Sl'H I.A (;OiVII>OSITI()N 



ces cellules, siliiccs en dcliois <lc Wvui, itiodiiisciil (((iishmiiiH'iil dc iioii- 

 vollos ([u;tnlil(''s dc njIcIIiis, cI Ics (■IrtiKMils ((ifcllcs .s('(irlc,iil soul iiiiK'tK's 



ISMir irsiiiiKT (Ml <iii('l(|(ic.s riiols cc (|iii csl icl.-ilil;. I;, lonnnlioii dii vilcllus, 

 dis(Mis (|(i(' Ic \il(<llus s(> coiisliliK' iKUlutil dc dcKx |)iiii<i!)('s dislincls ; d'uii 



(••IniKMil |)n>(,(»|.l;isin;i(i(|iH' (|iii lorn ssciilicllcmnil Ic (..ips dr l;i (■ciliil.'- 



ivul\ el (run dciiK.pJasinc (|iii sc (oiisliliic ,rini .rnias d(> in,Hi(T(-s imlrilivcs 



dcsliiK- a n(.(UTM- Ics piciinV'ics cdhdcs ciiihncmiaiiTs el IVnd.n liiHir. (>ii 



|)(Mnr,iil divisci- riiisK.iic dc r(M)-cn(-'sc (Pkn -laiid iioinhrc (raniiiKUix cii 

 (lcii\ |)(Ti(Mlcs liicii (lislmclcs : la [icnodc dc lornialion dii i-cnnc cl la !)("ri(.(lc 



i\v loriiiali Ic Wvui; dans ccllc sccondc pciiodc Ic -(tiiic ac(|iiicrl i;(-ii(Ta- 



Icnicni. (Ics dimensions pins (■(.nsidcral.lcs, cl, Ics clcnicnls rdifs vicnncnl 



s'lnnr an pn.loplasnic potn- roniici' avcc Ini Ic vilcllus. iTcsi encore pcndaiil 

 cell.' sccondc pc'riodc ([iic sc rorniciil Ics nicnd)rancs dc l^cnf, doni, 11 seta 

 ([ucslion l)ienl(')L 



Lc -crnic csl la parlic csscidicllc cl londanicnlale dc r<cid', pinstpril csl 

 le poiiK i\>- d('parl dc rcrnl.r>(Mi doiK il consliinc rccllcm(>nl la prcini<'rc 

 celhdc enibrvonnairc; il sc developpc, (FapnVs nn proc(Ml(' nniipie cl innTornic, 

 dans Ics classes Ics pins diverscs dn rci^n.c animal. II nVn csl pas dc m('mc 

 (111 dciil(.|»lasnic, (pii csl la parlic accessoire dn vilellns el ipii iic fail, pas 

 panic mlc-ranlcdc la cellule. 



Clic/ Ics oiseanv cl: Ics mammilcrcs, anssi l.icn (pie clicz nn ccrlaiit 



iioililtrc (ranimanx iidcrieins, Icis (pic Ics rnislacc's, Ics [Ncmalodcs, Ics 



IMaiiaircs cl Ics N('iiicrlcs, Ics clcn Is nnlrilils sc lornKMil a rinlcricnr 



iiK'Hic (111 proroplasm<> dn -<>rmc, ipii pnisc dans Ic liipiiil<> sanonin amliianl 

 Ics cicincnis lu'ccssaircs a jcur elahoralion. Vlais die/ Ics aiiimanx snpc- 

 ricms, nil ccrlain noml.rc (U> ces (d('nicnls sc Ironvenl, (l(\s Ic dcl.nl, en 



suspension dans Ic proloplas , dc I.ellc manicre (pill nVsl pas possible 



dc disliiii-iicr dans Ics liil.cs ovari(-ns niic re-ion spirialemcnl aircclcc a la 



formalion dcs i^crmcs, imc aiilrc an devclopp ides ek'nienls nnlrilils dn 



\ilcllns. 11 V a (nsioiH(.mpl(''le i\u Iravail pliysiolo-i(pic. 



Clic/ Ics aiiimanx inlcricnrs, an conlrairc, Ic i^mmiiic csl, loiil (rahoni mic 

 cellule |.rolo[)lasniali(pie pai lailcnieiil, liansparcnle. Ccsl plus lard seiileineni 



