| → we use descent in classing acknowledged varieties, however different 1859 1860 1861 1866 |
| although 1869 1872 |
|
| → be 1859 1860 1861 1866 |
| have but few characters in common; we use descent in classing acknowledged varieties, however different they may be 1869 1872 |
|
| → between the descendants from a common parent, 1859 1860 1861 1866 |
| OMIT 1869 1872 |
|
| → are permitted to 1859 1860 1861 1866 |
| OMIT 1869 1872 |
|
| → comparing 1859 1860 1861 1866 |
| finding the relations between 1869 1872 |
|
| → with a distinct group, 1859 1860 1861 1866 |
| and another, 1869 1872 |
|
| → in one great system; 1859 1860 1861 1866 |
| within a few great classes; 1869 1872 |
|
| ↑ 3 blocks not present in 1859 1860 1861 1866; present in 1869 1872 |
| Professor Häckel in his 'Generelle Morphologic'
and in several
other works, has recently brought his great knowledge and abilities to bear on what he calls phylogeny, or the lines of descent of all organic beings.
In drawing up the several series he trusts chiefly to embryological characters, but draws
aid from homologous and rudimentary organs, as well as from the successive periods at which the various forms of life first
appeared in our geological formations.
He has thus boldly made a great beginning, and shows us how classification will in the future be treated.
|
|
|
under one
→we use descent in classing acknowledged varieties, however different
they may
→be
from their
and I believe
element of descent is the hidden bond of connexion which naturalists have sought under the term of the Natural System. On this idea of the natural system being, in so far as it has been perfected, genealogical in its arrangement, with the grades of difference
→between the descendants from a common parent,
expressed by the terms genera, families, orders, &c., we can understand the rules which we are compelled to follow in our classification. We can understand why we value certain resemblances far more than others; why we
→are permitted to
use rudimentary and useless organs, or others of trifling physiological importance; why, in
→comparing
one group
→with a distinct group,
we summarily reject analogical or adaptive characters, and yet use
same characters within the limits of the same group. We can clearly see how it is that all living and extinct forms can be grouped together
→in one great system;
and how the several members of each class are connected together by the most complex and radiating lines of affinities. We shall never, probably, disentangle the inextricable web of
between the members of any one class; but when we have a distinct object in view, and do not look to some unknown plan of creation, we may hope to make sure but slow progress. ↑ |
|
|
| We have seen that the members of the same class, independently of their habits of life, resemble each other in the general plan of their
This resemblance is often expressed by the term "unity of type;" or by saying that the several parts and organs in the different species of the class are homologous. The whole subject is included under
|
