| → correlated with others, 1859 1860 1861 1866 1869 |
| in combination, 1872 |
|
| ↑ 1 blocks not present in 1859 1860 1861; present in 1866 1869 1872 |
| Thus, as Fritz Müller
has lately remarked, in the same group of crustaceans, Cypridina is furnished with a heart, whilst in two
closely allied genera, namely Cypris and Cytherea, there is no such organ; one species of Cypridina has well-developed branchiæ, whilst another species is destitute of them.
|
|
| → any in the classification of animals; 1859 1860 1861 1866 |
| all; 1869 1872 |
|
| → true. 1859 1860 1861 1869 1872 |
| true, though its importance has sometimes been exaggerated. 1866 |
|
| → The same fact holds good with flowering plants, of which the two main divisions have been founded on characters derived from the embryo,— on the number and position of the em- bryonic leaves or cotyledons, and on the mode of development of the plumule and radicle. 1859 1860 1861 |
| The general fact of the importance of embryological characters holds good with flowering plants, of which the two main divisions have been founded on differences in the embryo,— on the number and position of the cotyledons, and on the mode of development of the plumule and radicle. 1866 |
| Nevertheless their importance has sometimes been exaggerated; in order to show this, Fritz Müller arranged by the aid of such characters the great class of crustaceans, and the arrangement did not prove a natural one. 1869 |
|
|
not trouble themselves about the physiological value of the characters which they use in defining a
or in allocating any particular species. If they find a character nearly uniform, and common to a great number of forms, and not common to others, they use it as one of high value; if common to some lesser number, they use it as of subordinate value. This principle has been broadly confessed by some naturalists to be the true one; and by none more clearly than by that excellent botanist, Aug. St. Hilaire. If
characters are always found
→correlated with others,
though no apparent bond of
can be discovered between them, especial value is set on them. As in most groups of animals, important organs, such as those for propelling the blood, or for
it, or those for propagating the race, are found nearly uniform, they are considered as highly serviceable in classification; but in some groups
all these, the most important vital organs, are found to offer characters of quite subordinate value. ↑
|
|
| We can see why characters derived from the embryo should be of equal importance with those derived from the adult, for
of course
all
But it is by no means obvious, on the ordinary view, why the structure of the embryo should be more important for this purpose than that of the adult, which alone plays its full part in the economy of nature. Yet it has been strongly urged by those great naturalists, Milne Edwards and Agassiz, that
characters are the most important of
→any in the classification of animals;
and this doctrine has very generally been admitted as
→true. →The same fact holds good with flowering plants, of which the two main divisions have been founded on characters derived from the embryo,— on the number and position of the em- bryonic leaves or cotyledons, and on the mode of development of the plumule and radicle.
|
