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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,
each other much more closely than do the mature insects; but in
the embryos are active, and
been adapted for special lines of
→life sometimes differ much from each other. A trace of the
of embryonic
lasts till a rather late age: thus birds of the same genus, and of
allied genera, often resemble each other in their
→immature
plumage; as we see in the spotted feathers in the
→young of 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
kind in
thus the
leaves of the ulex or furze, and the first leaves of the
are pinnate or divided like the ordinary leaves of the
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