| → 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 |
|
| → Silurian stratum— 1866 1869 |
| Silurian strata are discovered— 1860 1861 |
| Cambrian strata— 1872 |
|
| →
Areas,
1866 1869 |
|
areas
,
1859 1861 |
|
areas
.
1860 |
|
Areas
,
1872 |
|
|
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
→Silurian stratum—
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
|
