Origin of Species Variorum

→ during a long course of descent 1859 1860 1861 1866

OMIT 1869 1872

→ legs, or from some simple appendage, is 1859 1860 1861

though simple legs, is 1866

though extremely simple legs, is 1869

though extremely simple legs, is in part 1872

←Subtitle not present 1859 1860 1861 Embryology and Development . 1866 1869 1872

↑ 1 blocks not present in 1859 1860 1861; present in 1866 1869 1872

This is one of the most important departments of natural history.

→ casually remarked that certain organs 1859 1860 1861

remarked that various parts and organs of the same individual animal are during an early embryonic period exactly like each other, but become 1866

stated that various parts and organs 1869

stated that various parts 1872

→ individual, which when mature become widely different and serve for different purposes, are in the embryo exactly alike. 1859 1860 1861

adult state widely different and serve for widely different purposes. 1866

same individual are exactly like each other during an early embryonic period, but in the adult state become widely different and serve for widely different purposes. 1869

same individual which are exactly alike during an early embryonic period, become widely different and serve for widely different purposes in the adult state. 1872

→ circumstance mentioned by Agassiz, 1859 1860

statement made by Von Baer, 1861

→ having forgotten to ticket the 1859 1860

"the 1861

→ some vertebrate animal, he cannot now tell whether it be that of a mammal, bird, or reptile. 1859 1860

mammalia, of birds, lizards, and snakes, probably also of chelonia, are in their earliest states exceedingly like one another, both as a whole and in the mode of development of their parts; so much so, in fact, that we can often distinguish the embryos only by their size. 1861

→ life. 1859 1860 1861

life sometimes differ much from each other. 1866 1869

→ first and second 1859 1860 1861 1866

immature 1869 1872

→ thrush 1859 1860 1861 1866

young of the thrush 1869 1872

→ are 1859 1860 1861 1866 1869

when adult are 1872

→ can 1859 1860

or spots can 1861 1866 1869 1872

→ lion. 1859 1860

lion and the puma. 1861 1866 1869 1872

may be used literally; and the wonderful fact of the jaws, for instance, of a crab retaining numerous characters, which they

probably would

would probably

have retained through inheritance, if they had really been metamorphosed →during a long course of descent from true →legs, or from some simple appendage, is explained. → ↑

Embryology .—

It has already been →casually remarked that certain organs in the →individual, which when mature become widely different and serve for different purposes, are in the embryo exactly alike. The embryos, also, of distinct animals within the same class are often strikingly similar: a better proof of this cannot be given, than a →circumstance mentioned by Agassiz, namely, that →having forgotten to ticket the

embryos

embryo

of →some vertebrate animal, he cannot now tell whether it be that of a mammal, bird, or reptile. The vermiform larvæ of moths, flies, beetles,

&c.,

generally resemble

resemble

each other much more closely than do the mature insects; but in

these

the

cases

case

~~of larvæ,~~

of larvæ,

the embryos are active, and

from having

have

been adapted for special lines of →life. A trace of the

jaw

law

of embryonic

resemblance

resemblance,

occasionally

sometimes

lasts till a rather late age: thus birds of the same genus, and of

~~closely~~

closely

allied genera, often resemble each other in their →first and second plumage; as we see in the spotted feathers in the →thrush group. In the cat tribe, most of the species →are striped or spotted in lines; and stripes →can be plainly distinguished in the whelp of the →lion. We occasionally though rarely see something of

the same

this

kind in

plants;

plants:

thus the

first

embryonic

leaves of the ulex or furze, and the first leaves of the

phyllo- dineous

phyllodineous

acacias,