From the remarks
above
made we can see how by
alterations alterations 1866 | changes 1869 1872 |
of structure in the young, in conformity with
altered altered 1866 | changed 1869 1872 |
habits of life, together with inheritance at corresponding ages,
the metamorphoses of certain animals might first have been acquired, and subsequently transmitted to numerous modified descendants. the metamorphoses of certain animals might first have been acquired, and subsequently transmitted to numerous modified descendants. 1866 |
animals in certain cases might come to pass through stages of development, perfectly distinct from their primordial, adult condition. 1869 |
animals might come to pass through stages of development, perfectly distinct from the primordial condition of their adult progenitors. 1872 |
↑6 blocks not present in 1859 1860 1861 1866 1869; present in 1872 | Most of our best authorities are now convinced that the various larval and pupal stages of insects have thus been acquired through adaptation, and not through inheritance from some ancient form.
The curious case of Sitaris— a beetle which passes through certain unusual stages of development— will illustrate how this might occur.
The first larval form is described by M. Fabre, as an active, minute insect, furnished with six legs, two long antennæ, and four eyes.
These larvæ are hatched in the nests of bees; and when the male-bees emerge from their burrows, in the spring, which they do before the females, the larvæ spring on them, and afterwards crawl on to the females whilst paired with the males.
As soon as the female bee deposits her eggs on the surface of the honey stored in the cells, the larvæ of the Sitaris leap on the eggs and devour them.
Afterwards they undergo a complete change; their eyes disappear; their legs and antennæ become rudimentary, and they feed on honey; so that they now more closely resemble the ordinary larvæ of insects; ultimately they undergo a further transformation, and finally emerge as the perfect beetle.
|
Fritz Müller, who has recently discussed this
whole
subject with much ability,
goes so far as to goes so far as to 1866 |
OMIT 1869 |
believe believe 1866 | believes 1869 |
that the progenitor of all insects
probably probably 1866 | probably 1869 |
resembled an adult insect, and that the caterpillar or
maggot,
and and 1866 |
stages, as well as the 1869 |
cocoon or pupal stages, have subsequently been acquired; but from this view many naturalists, for instance Sir J. Lubbock, who has likewise recently discussed this subject, would, it is probable, dissent. That certain unusual stages in the metamorphoses of insects have
arisen from arisen from 1866 |
been acquired through 1869 |
adaptations adaptations 1866 | adaptation 1869 |
to peculiar habits of
life
can
hardly be
doubted: doubted: 1866 | a doubt: 1869 |
thus the first larval form of a certain beetle, the Sitaris, as described by M. Fabre, is
a minute, active a minute, active 1866 |
an active, minute 1869 |
insect, furnished with six legs, two long antennæ, and four eyes. These larvæ are hatched in the
nest
of
a
bee;
and when the male-bees emerge
in the spring in the spring 1866 |
OMIT 1869 |
from their
burrows, burrows, 1866 | burrows 1869 |
which
they
do do 1866 |
spring, which they do 1869 |
before the females, the larvæ spring on them, and afterwards
take an early and natural opportunity of crawling on to the female-bees. take an early and natural opportunity of crawling on to the female-bees. 1866 |
crawl on the females whilst paired with the males. 1869 |
When the latter When the latter 1866 |
As soon as the females 1869 |
lay their
eggs,
one in each cell, one in each cell, 1866 |
OMIT 1869 |
on the surface of the
contained contained 1866 | contained 1869 |
honey,
the larva the larva 1866 |
stored in their cells, the larvæ of the Sitaris 1869 |
leaps
on the
egg
and
devours
it.
It then It then 1866 |
Afterwards these larvæ 1869 |
undergoes undergoes 1866 | undergo 1869 |
a complete change;
its
eyes disappear;
its
legs and antennæ become rudimentary, and
it
feeds
on honey; so that
it
now more closely
resembles resembles 1866 | resemble 1869 |
the ordinary larvæ of insects; ultimately
it
undergoes undergoes 1866 | undergo 1869 |
further further 1866 | a further 1869 |
transformations, transformations, 1866 | transformation, 1869 |
and finally
emerges
as
a
perfect beetle. Now, if an insect, undergoing transformations like those of the Sitaris,
had been had been 1866 |
were to become 1869 1872 |
the progenitor of
the
whole
great
class of insects,
the general the general 1866 | their 1869 | the 1872 |
course of
development, development, 1866 | develop- ment 1869 | development 1872 |
|