VARIATION AND DIFFERENTIATION 181
_:
in
media, -for
blood or … water.
An
organisi‘h isof suchÏ-îiinstable components and the
marvel is, that it should remain at all constant, not that it
,
should vary.
With the formation of structures composed
mainly of inorganic materials, more xity or permanency
has been obtained, but until these are formed in the
.
stages of each individual the organism is plastic and ready
to change under the inuence of the physical and chemical
surroundings…
,
.
.
-
,
-7
Starting from this basis Heincke in his great work on the
_
Herring sought to establishtwo parallel series ; on the one
.
side the variations ‘in
,.
the characters, on the other _.the
variàtions'hi the external surroundings. From the former
lie. hoped to obtain an average condition representing arace,
Oi*it may be a species, from the latter an average of all the
inf—ernces, physical, chemical, and biological, aecting the
young larvæ.
The racial characters and environment are
inseparable.
_
On general grounds one would think that this should give
a… good working basisfor the study of variations;andtheiiÈ_
butthe practical difculties ;in- the way of formmg
_
immense,, and—no one 88 yet has
.
tried togiÿè any idea of the average of the external inuence$,_
During the past
“moreover,the tendency has
.
been for workers to leave these
of account
L
and to concentrate attention on the nature of;thê
It is conceivable, indeed,_that organisms are now "‘sïo well'
adapted to their respective environments, right from the
earliest stages, that the external inuencés can -èect_ little
during the orderly progress of
Onthlsv1ew the inherited constitution is everything and“ the
,
-
matealbase of heredity has been traced to the chromosomes
of the germplasm,whiCh play such an important pârtiri,the
'
structure àh—d buildingup of the
It,
by some,
sex; and
can {be referred back to
presence _.of part1cularkmdsof
;“.Chïômosomes in theÊgerm,
',
Before, the ŒUè9—àOf
çan’
,
'
z_
_:
in
media, -for
blood or … water.
An
organisi‘h isof suchÏ-îiinstable components and the
marvel is, that it should remain at all constant, not that it
,
should vary.
With the formation of structures composed
mainly of inorganic materials, more xity or permanency
has been obtained, but until these are formed in the
.
stages of each individual the organism is plastic and ready
to change under the inuence of the physical and chemical
surroundings…
,
.
.
-
,
-7
Starting from this basis Heincke in his great work on the
_
Herring sought to establishtwo parallel series ; on the one
.
side the variations ‘in
,.
the characters, on the other _.the
variàtions'hi the external surroundings. From the former
lie. hoped to obtain an average condition representing arace,
Oi*it may be a species, from the latter an average of all the
inf—ernces, physical, chemical, and biological, aecting the
young larvæ.
The racial characters and environment are
inseparable.
_
On general grounds one would think that this should give
a… good working basisfor the study of variations;andtheiiÈ_
butthe practical difculties ;in- the way of formmg
_
immense,, and—no one 88 yet has
.
tried togiÿè any idea of the average of the external inuence$,_
During the past
“moreover,the tendency has
.
been for workers to leave these
of account
L
and to concentrate attention on the nature of;thê
It is conceivable, indeed,_that organisms are now "‘sïo well'
adapted to their respective environments, right from the
earliest stages, that the external inuencés can -èect_ little
during the orderly progress of
Onthlsv1ew the inherited constitution is everything and“ the
,
-
matealbase of heredity has been traced to the chromosomes
of the germplasm,whiCh play such an important pârtiri,the
'
structure àh—d buildingup of the
It,
by some,
sex; and
can {be referred back to
presence _.of part1cularkmdsof
;“.Chïômosomes in theÊgerm,
',
Before, the ŒUè9—àOf
çan’
,
'
z_