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theso-calleddormant(winter)eggswith2nchromosomeseach.Undersuitable
conditionsthoseeggswillhatchintoamicticfemales(2nchromosomes)consti-
tutinganewgenerationofamicticfemales.Thisway,thenextcycleofdiploid
(ameiotic)parthenogeneticreproductionbegins.Amicticfemalesmayalsode-
velopdirectlyfromtheso-calledsummeramicticeggand,viaparthenogenesis,
producenewgenerationsofamicticfemales.Thisiswhattheclassicheterogony
inmostmonogonontrotiferslookslike(BIRKY1964)(Fig.18A).Heterogony
insomerotiferspeciesmaybestillmorecomplex,particularlywithrespectto
theamicticcycle.
AsshownbyBOGOSLOVSKIj(1959,1960,1961),numerousspecieshave-in
additiontoamicticandmicticfemales-athirdtypeoffemale,theso-calledam-
photericfemale.Thesemayhatchfromdormant(winter)eggslaidbythemictic
females,orfromamictic(summer)eggslaidbyagenerationofamicticfemales.
Amphotericfemaleslayeggsrepresentingoneofthefollowingthreetypes:
a)amicticeggs(2n)which,parthenogenetically,giverisetosubsequentgenera-
tionsofamicticfemales;
b)maleandfemalemicticeggswithnchromosomes;themaleeggs,without
fertilisation,hatchintomalescapableofproducingspermatozoa,whilethefe-
maleeggsgiverisetomicticfemaleswhichproducetheso-calledwintereggs,
abletodeveloponlyaftertheyhavebeenfertilised;
c)dormanteggswith2nchromosomes,producedbyfemalesfertilisedbymales
hatchedfromthewintereggs.
BOGOSLOVSKIj(1961)contendsthatitisnotineachspeciesthateveryampho-
tericfemalelaysthethreetypesofeggs,sothat:
a)femalesof,e.g.,Brachionusurceolaris,Epiphanesbrachionus,Keratella
cochlearis,K.quadrata,Brachionuscalyciflorus,B.quadridentatus,and
B.angularislaythedormanteggsonly;
b)femalesofthespeciesbelongingtothegenusAsplanchnalayeitherdormant
eggsormaleorfemaleeggs;
c)femalesofotherspecieslayeggsofallthethreetypes:dormant,maleorfemale,
andamictic;thisisthecasein,e.g.,SinantherinasocialisandConochiloides
coenobasis.
SUDZUKI(1964)reportedasmanyassixtypesoffemaletobefoundin
monogonontrotifers:
a)juvenilefemales,incapableofegglaying;
b)femalesthatlayamicticeggs;
c)femaleslaying“pseudosexual”eggs;
d)femalesthatproduce“male”eggs;
e)femalescapableoflayingbothmicticandamicticeggs;
f)femalesthatproducedormanteggs.
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