Origin of Species Variorum

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

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

→ life sometimes differ much from each other. 1866 1869

life. 1859 1860 1861

→ 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

→ or spots can 1861 1866 1869 1872

can 1859 1860

→ lion and the puma. 1861 1866 1869 1872

lion. 1859 1860

the statement

that

by Von

Baer

Baer,

~~namely,~~

namely,

that "the embryos of 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. ↑ In my possession are two little embryos in spirit, whose names I have omitted to attach, and at present I am quite unable to say to what class they belong. They may be lizards or small birds, or very young mammalia, so complete is the similarity in the mode of formation of the head and trunk in these animals. The extremities, however, are still absent in these embryos. But even if they had existed in the earliest stage of their development we should learn nothing, for the feet of lizards and mammals, the wings and feet of birds, no less than the hands and feet of man, all arise from the same fundamental form." The vermiform larvæ of moths, flies, beetles,

&c.,

resemble

generally 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

have

from having

been adapted for special lines of →life sometimes differ much from each other. A trace of the

jaw

law

of embryonic

resemblance

resemblance,

sometimes

occasionally

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 →or spots can be plainly distinguished in the whelp of the →lion and the puma. We occasionally though rarely see something of

the same

this

kind in

plants;

plants:

thus the

embryonic

first

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

phyllo- dineous

phyllodineous

acaceas,

acacias,

are pinnate or divided like the ordinary leaves of the

leguminousæ.

leguminosæ.