AND THE WEB îOF LIFE
'
928753
years old with a
male one = year old, only 50 —fe_rhales
were obtained in 800Ï=0spring, but in'thé neXt broodïr‘om
the same male, then tw0èyears Old, he obtained 300 females
in 400.
On pairing-laiäge, late—ripe
(Pœcilia) 76 per cent. of the o’Sprig were femelles-;
middle large females With the: same kind of
92 per cent. of
,
Small males always gave a-larger_ ,
_
proportion of
In 7generalÿ“the-percentage of5zinales
is greater'inf the spring Very low in the autumn (viviparous
Carplings);Ï
course,» is also. the
poultry breede_rsl . :
'
.'
.
.
=
‘
,
F rom; an‘_ examination ofwell over
thousand
spaWni‘ng lshes- of various species (Trout,
gonus and Î"Salvelinus) Surbeckfound that the proportions
of the sexes varied COnsiderably in the different lakes of
Switzerland, Item almost equality in the case of the Seato nearly 700 males to 100 females in-the case of
Coregonus (1913, 1914).
,
Following the result 0f=Thumm’s
_
_
experiments, this‘ disproportion
the main…to
of usingthe milt of the fsmaller
with the ‘}
roeof larger
But ==this-is admittedly=only aupartialÏ
Ü
…
explanatron IÏn4the
]äfvi(1920) has=fod
_
the…Coregon‘us there,— 271 males
t0and :ffom other 1 data ’it
rule that
,
the}males‘ofmost'_freshwater species
’
,
over the females, even”underænatural
*
"
'
,
A. curious thing;is‘, that the —“males mature "earlier fand
,
die younger,— in s0me cases at least. ]ärvi found: onlÿ_a
Small proportion of males in their fth”year and thereafter
-
only fethales, but the nümbèrs were small; In the remark—
’
Salmonoid Plecoglossus of Ayu,.which— normally
only 01ie,year, Some manage to survive the second
wint€rin
and these are always females (N
;
=
.
What the “proportions of the sexes areinwarm6fÿclihmtes
is not "So “well-known. = »AÇcotdingvto a»
'G'.
Boulenger (1924) Îtheïfenaales of _;Xiphophorùs “(a Mexican
Cyprinodont) outnumber- the '.rnales' bÿ1four to “one”; = If :this
'
928753
years old with a
male one = year old, only 50 —fe_rhales
were obtained in 800Ï=0spring, but in'thé neXt broodïr‘om
the same male, then tw0èyears Old, he obtained 300 females
in 400.
On pairing-laiäge, late—ripe
(Pœcilia) 76 per cent. of the o’Sprig were femelles-;
middle large females With the: same kind of
92 per cent. of
,
Small males always gave a-larger_ ,
_
proportion of
In 7generalÿ“the-percentage of5zinales
is greater'inf the spring Very low in the autumn (viviparous
Carplings);Ï
course,» is also. the
poultry breede_rsl . :
'
.'
.
.
=
‘
,
F rom; an‘_ examination ofwell over
thousand
spaWni‘ng lshes- of various species (Trout,
gonus and Î"Salvelinus) Surbeckfound that the proportions
of the sexes varied COnsiderably in the different lakes of
Switzerland, Item almost equality in the case of the Seato nearly 700 males to 100 females in-the case of
Coregonus (1913, 1914).
,
Following the result 0f=Thumm’s
_
_
experiments, this‘ disproportion
the main…to
of usingthe milt of the fsmaller
with the ‘}
roeof larger
But ==this-is admittedly=only aupartialÏ
Ü
…
explanatron IÏn4the
]äfvi(1920) has=fod
_
the…Coregon‘us there,— 271 males
t0and :ffom other 1 data ’it
rule that
,
the}males‘ofmost'_freshwater species
’
,
over the females, even”underænatural
*
"
'
,
A. curious thing;is‘, that the —“males mature "earlier fand
,
die younger,— in s0me cases at least. ]ärvi found: onlÿ_a
Small proportion of males in their fth”year and thereafter
-
only fethales, but the nümbèrs were small; In the remark—
’
Salmonoid Plecoglossus of Ayu,.which— normally
only 01ie,year, Some manage to survive the second
wint€rin
and these are always females (N
;
=
.
What the “proportions of the sexes areinwarm6fÿclihmtes
is not "So “well-known. = »AÇcotdingvto a»
'G'.
Boulenger (1924) Îtheïfenaales of _;Xiphophorùs “(a Mexican
Cyprinodont) outnumber- the '.rnales' bÿ1four to “one”; = If :this