Origin of Species Variorum

↑ 5 blocks not present in 1859 1860 1861 1872; present in 1866 1869

Fritz Müller, who has recently discussed this whole subject with much ability, goes so far as to believe that the progenitor of all insects probably resembled an adult insect, and that the caterpillar or maggot, and 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 adaptations to peculiar habits of life can hardly be doubted: thus the first larval form of a certain beetle, the Sitaris, as described by M. Fabre, is a minute, active 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 from their burrows, which they do before the females, the larvæ spring on them, and afterwards take an early and natural opportunity of crawling on to the female-bees. When the latter lay their eggs, one in each cell, on the surface of the contained honey, the larva leaps on the egg and devours it. It then undergoes a complete change; its eyes disappear; its legs and antennæ become rudimentary, and it feeds on honey; so that it now more closely resembles the ordinary larvæ of insects; ultimately it undergoes further transformations, and finally emerges as a perfect beetle.

→ were to become 1869 1872

had been 1866

→ of the new class would be 1872

and especially that of the first larval stage, would probably have been 1866

would probably be 1869

→ of our existing insects; and 1872

is actually the case; and it should be especially noted that 1866

it now is; and 1869

→ certainly would not 1869 1872

would not have 1866

→ adult and ancient form. 1872

insect. 1866

adult and ancient insect. 1869

→ OMIT 1869 1872

ancient and adult 1866

→ group in its adult state. 1872

group. 1866

group in its adult condition. 1869

→ at first as larvæ under the 1869 1872

in their first larval state under a similar 1866

→ at some very remote period an 1872

an 1866 1869

→ and 1872

at a remote period, and has 1866

at some very remote period, and 1869

→ OMIT 1869 1872

through long-continued modification 1866

→ these animals 1869 1872

all the members in these four great classes 1866

→ can be arranged within a few great classes; 1869 1872

on this earth have to be classed together, 1859 1860 1861

on this earth, have to be classed together, 1866

→ within each class have, according to our theory, 1872

have 1859 1860 1861 1866

within each class have, according to our theory, formerly 1869

→ together by fine 1869 1872

by the finest 1859 1860

by fine 1861 1866

→ OMIT 1869 1872

on my view 1859 1860 1861

on this view 1866

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. ↑ Now, if an insect, undergoing transformations like those of the Sitaris, →were to become the progenitor of

the

whole

great

new

class of insects,

the general

their

the

course of

development,

develop- ment

development

→of the new class would be widely different from

what

that

→of our existing insects; and the first larval stage →certainly would not

represented

represent

the

adult

former

condition of any →adult and ancient form.

On the other hand it is

probable

highly probable

that with many

groups of

....

animals the

earlier

embryonic or

larval stages

....

show us, more or less completely, the

form

state

condition

of the →OMIT progenitor of the whole →group in its adult state. In the

enormous

great

class of the Crustacea, forms wonderfully distinct from each other,

as the

namely,

suctorial parasites, cirripedes, entomostraca, and even the malacostraca, appear →at first as larvæ under the

nauplius form;

nauplius-form;

and as these larvæ

feed

live

and

live

feed

in the open sea, and are not adapted for any peculiar habits of life, and from other reasons assigned by Fritz

Müller,

it is probable that →at some very remote period an independent adult animal, resembling the

nauplius,

Nauplius,

formerly

....

existed

existed,

→and subsequently produced, →OMIT along several divergent lines of descent, the

several

....

above-named great Crustacean groups. So again it is probable, from what we know of the embryos of mammals, birds, fishes, and reptiles, that →these animals are the modified descendants of some

one

....

ancient progenitor, which was furnished in its adult state with branchiæ,

had

....

a swim-bladder, four

simple

fin-like

limbs, and a long

tail

tail,

fitted

all fitted

for an aquatic life.

As all the organic beings, extinct and recent, which have ever

lived

lived,

→can be arranged within a few great classes; and as all →within each class have, according to our theory, been connected →together by fine gradations, the best,

or indeed,

or,

and,

if our collections were nearly perfect, the only possible arrangement, would be

genealogical.

genealogical;

Descent

descent

being →OMIT the hidden bond of connexion which naturalists have been seeking under the term of the

natural

Natural

system.

System.

On this view we can understand how it is that, in the eyes of most

natu- ralists,

naturalists,

the structure of the embryo is even more important for classification