VARIATION AND
177
j
pr‘o‘bable average for"“the species,“ at the time when these-—
observations were made, would aslikelyas not lie between
the values Air, that is, between 114711 and 1145745,
which means a very small range of Variation, c0rresponding
to the large number of spécimens examined; »î1£ We? take
,
'
three times the probable error, then the
about ,
’
,
20
to
1
that the true“ average lies between
-,
'
*
Il4—'779'
,
It is by means of such calculations, if the material is
sufciently large to be representative, thatracës Or varieties
of a Species can be distinguished. _Thus, if
’
-
;{’jÎ_=
of Eels from different parts of Europe gave averages lying'
”
outside these probable limits, we should beentitled
'
,
«the‘m, even though the frequencies might overlap, as separate
,
races Which had {grown up under different conditions:
]ohs. SQhdt has made such a comparison between Eels
from the Mediterranean and 'Eels from northern waters, -
-
and found that;äthe probable average Was the same in
,
,
case. , Î He
entitled to chine
'
all the EuropeanEelsbelongto thesamestock born under
the same;.c_ôbdîoñsgÿfh3ç*ti3_,“6ùt
,
,
, ,
—
.
Guppdpytnye
Wbtbeeddeb beb bed ee: , -
’uèe‘fiésäiæs in thefactthat from1t we
,Ï
__
__
the factor Ï, the real frequencies
—
_
o,
-
-
:
according to the normal curve of frequency (Gauss’ Curve).
"
,.
In this way the observed and normal values
Compared
—
as follows :
_
”"”—.
110
111
ma
113
114
115
116
117
1—_1___9___
0b'served freq.
1
17
89
352
719
865
500
192
36
4
Normalÿfœq.
1
16
101
358
716
815
527
193
40
.5
'
,
’
It will be seen that, except at the twoï‘adjacent frequt‘aiï‘c‘iies,
115 and 116, the agreement, is extremely good, Indeed,g
'ifjwe allow f0rthe personal
agreemer‘1tis a’s”
'
perfect as one can hope for. Whatever maybe thefc_auses
of the whole
the
in a_‘rèmarkable
‘
'