| → and several other highly competent judges insist 1869 1872 |
| insists 1859 1860 1861 1866 |
|
| → nearly parallel with 1869 1872 |
| in some degree parallel to 1859 1860 1861 |
| in some degree parallel with 1866 |
|
| ↑ 3 blocks not present in 1869 1872; present in 1859 1860 1861 1866 |
| I must follow Pictet and Huxley in thinking that the truth of this doctrine is very
far from proved.
Yet I fully expect to see it hereafter confirmed, at least in regard to subordinate groups,
which have branched off from each other within comparatively recent times.
For this doctrine of Agassiz accords well
with the theory of natural selection.
|
|
| → proof. 1860 1861 1866 1869 1872 |
| proof. Seeing, for instance, that the oldest known mammals, reptiles, and fish strictly belong to their own proper classes, though some of these old forms are in a slight degree less distinct from each other than are the typical members of the same groups at the present day, it would be vain to look for animals having the common embryological character of the Vertebrata, until beds far beneath the lowest Silurian strata are discovered— a discovery of which the chance is very small. 1859 |
|
| → rich in fossils are discovered far 1866 1869 1872 |
| far 1860 1861 |
|
| → Cambrian strata— 1872 |
| Silurian strata are discovered— 1860 1861 |
| Silurian stratum— 1866 1869 |
|
| →
Areas
,
1872 |
|
areas
,
1859 1861 |
|
areas
.
1860 |
|
Areas,
1866 1869 |
|
|
most skilful
from an examination of the species of the two
could not have foreseen this result. |
|
| Agassiz
→and several other highly competent judges insist
that ancient animals resemble to a certain extent the embryos of recent animals
the same classes;
that the geological succession of extinct forms is
→nearly parallel with
the embryological development of
forms. This view accords admirably well with our theory. ↑
In a future chapter I shall attempt to show that the adult differs from its embryo, owing to variations
at a not early age, and
inherited at a corresponding age. This process, whilst it leaves the embryo almost unaltered, continually adds, in the course of successive generations, more and more difference to the adult. |
|
| Thus the embryo comes to be left as a sort of picture, preserved by nature, of the
and less modified condition of
This view may be true, and yet
may never be capable of
→proof. Seeing, for instance, that the oldest known mammals, reptiles, and
strictly belong to their
proper classes, though some of these old forms are in a slight degree less distinct from each other than are the typical members of the same groups at the present day, it would be vain to look for animals having the common embryological character of the Vertebrata, until beds
→rich in fossils are discovered far
beneath the lowest
→Cambrian strata—
a discovery of which the chance is
small. |
|
→
Areas
,
|
| Mr. Clift many years ago showed that the fossil mammals from the Australian caves were closely allied to the living marsupials of that continent. In South America, a similar relationship is manifest, even to an uneducated eye, in the gigantic pieces of
like those of the armadillo, found in several parts of La Plata; and Professor Owen has shown in the most striking manner that most of the fossil mammals, buried there in such numbers, are related to South American types. This relationship is even more clearly seen in the wonderful collection of fossil bones made by MM. Lund and Clausen in the caves of Brazil. I was so much impressed with these facts that I strongly insisted, in 1839 and 1845, on this "law of the succession of types,"— on "this wonderful relationship in the same continent between the dead and the living." Professor Owen has subsequently extended the same generalisation to the mammals of the Old World. We see the same law in this
restorations of the extinct and gigantic birds of New Zealand. We
|
