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Export to Excel select * from OriginOfSpecies where ordinal = '10' order by subject, title, ordinal limit 116, 4 (Page 30: Row)
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13 - Mutual Affinities of Organic Beings: Morphology: Embryology: Rudimentary Or 13-02 - Natural system 10 Naturalists try to arrange the species, genera, and families in each class, on what is called the Natural System.

But what is meant by this system?

Some authors look at it merely as a scheme for arranging together those living objects which are most alike, and for separating those which are most unlike; or as an artificial means for enunciating, as briefly as possible, general propositions, that is, by one sentence to give the characters common, for instance, to all mammals, by another those common to all carnivora, by another those common to the dog-genus, and then by adding a single sentence, a full description is given of each kind of dog.

dog
dog


The ingenuity and utility of this system are indisputable.

But many naturalists think that something more is meant by the Natural System; they believe that it reveals the plan of the Creator; but unless it be specified whether order in time or space, or what else is meant by the plan of the Creator, it seems to me that nothing is thus added to our knowledge.

Such expressions as that famous one of Linnaeus, and which we often meet with in a more or less concealed form, that the characters do not make the genus, but that the genus gives the characters, seem to imply that something more is included in our classification, than mere resemblance.

Carl Linnaeus
Carl Linnaeus


I believe that something more is included; and that propinquity of descent, the only known cause of the similarity of organic beings, is the bond, hidden as it is by various degrees of modification, which is partially revealed to us by our classifications.
13 - Mutual Affinities of Organic Beings: Morphology: Embryology: Rudimentary Or 13-03 - Rules and difficulties in classification, explained on the theory of descent with modification 10 Let us now consider the rules followed in classification, and the difficulties which are encountered on the view that classification either gives some unknown plan of creation, or is simply a scheme for enunciating general propositions and of placing together the forms most like each other.

It might have been thought (and was in ancient times thought) that those parts of the structure which determined the habits of life, and the general place of each being in the economy of nature, would be of very high importance in classification.

Nothing can be more false.

No one regards the external similarity of a mouse to a shrew, of a dugong to a whale, of a whale to a fish, as of any importance.

mouse
mouse

shrew
shrew

dugong
dugong

whale
whale

fish
fish
13 - Mutual Affinities of Organic Beings: Morphology: Embryology: Rudimentary Or 13-04 - Classification of varieties 10 In confirmation of this view, let us glance at the classification of varieties, which are believed or known to have descended from one species.

These are grouped under species, with sub-varieties under varieties; and with our domestic productions, several other grades of difference are requisite, as we have seen with pigeons.

The origin of the existence of groups subordinate to groups, is the same with varieties as with species, namely, closeness of descent with various degrees of modification.

Nearly the same rules are followed in classifying varieties, as with species.

Authors have insisted on the necessity of classing varieties on a natural instead of an artificial system; we are cautioned, for instance, not to class two varieties of the pine-apple together, merely because their fruit, though the most important part, happens to be nearly identical; no one puts the swedish and common turnips together, though the esculent and thickened stems are so similar.

pineapple
pineapple

turnip
turnip


Whatever part is found to be most constant, is used in classing varieties: thus the great agriculturist Marshall says the horns are very useful for this purpose with cattle, because they are less variable than the shape or colour of the body, &c.; whereas with sheep the horns are much less serviceable, because less constant.

cattle
cattle

sheep
sheep


In classing varieties, I apprehend if we had a real pedigree, a genealogical classification would be universally preferred; and it has been attempted by some authors.

For we might feel sure, whether there had been more or less modification, the principle of inheritance would keep the forms together which were allied in the greatest number of points.

In tumbler pigeons, though some sub-varieties differ from the others in the important character of having a longer beak, yet all are kept together from having the common habit of tumbling; but the short-faced breed has nearly or quite lost this habit; nevertheless, without any reasoning or thinking on the subject, these tumblers are kept in the same group, because allied in blood and alike in some other respects.

Tumbler Pigeon
Tumbler Pigeon

Short Faced Tumbler Pigeon
Short Faced Tumbler Pigeon


If it could be proved that the Hottentot had descended from the Negro, I think he would be classed under the Negro group, however much he might differ in colour and other important characters from negroes.
13 - Mutual Affinities of Organic Beings: Morphology: Embryology: Rudimentary Or 13-05 - Descent always used in classification 10 With species in a state of nature, every naturalist has in fact brought descent into his classification; for he includes in his lowest grade, or that of a species, the two sexes; and how enormously these sometimes differ in the most important characters, is known to every naturalist: scarcely a single fact can be predicated in common of the males and hermaphrodites of certain cirripedes, when adult, and yet no one dreams of separating them.

cirripede
cirripede


The naturalist includes as one species the several larval stages of the same individual, however much they may differ from each other and from the adult; as he likewise includes the so-called alternate generations of Steenstrup, which can only in a technical sense be considered as the same individual.

Japetus Steenstrup
Japetus Steenstrup


He includes monsters; he includes varieties, not solely because they closely resemble the parent-form, but because they are descended from it.

He who believes that the cowslip is descended from the primrose, or conversely, ranks them together as a single species, and gives a single definition.

cowslip
cowslip

primrose
primrose


As soon as three Orchidean forms (Monochanthus, Myanthus, and Catasetum), which had previously been ranked as three distinct genera, were known to be sometimes produced on the same spike, they were immediately included as a single species.

orchid
orchid