The Origin of Species - Charles Darwin (ebook audio reader txt) 📗

id="tarsus" epub:type="glossterm"> Tarsus

(pl. Tarsi): The jointed feet of articulate animals, such as insects.

Teleostean Fishes

Fishes of the kind familiar to us in the present day, having the skeleton usually completely ossified and the scales horny.

Tentacula Tentacles

Delicate fleshy organs of prehension or touch possessed by many of the lower animals.

Tertiary

The latest geological epoch, immediately preceding the establishment of the present order of things.

Trachea

The windpipe or passage for the admission of air to the lungs.

Tridactyle

Three-fingered, or composed of three movable parts attached to a common base.

Trilobites

A peculiar group of extinct crustaceans, somewhat resembling the woodlice in external form, and, like some of them, capable of rolling themselves up into a ball. Their remains are found only in the Palaeozoic rocks, and most abundantly in those of Silurian age.

Trimorphic

Presenting three distinct forms.

Umbelliferae

An order of plants in which the flowers, which contain five stamens and a pistil with two styles, are supported upon footstalks which spring from the top of the flower stem and spread out like the wires of an umbrella, so as to bring all the flowers in the same head (Umbel) nearly to the same level. (Examples, parsley and carrot.)

Ungulata

Hoofed quadrupeds.

Unicellular

Consisting of a single cell.

Vascular

Containing blood-vessels.

Vermiform

Like a worm.

Vertebrata Vertebrate Animals

The highest division of the animal kingdom, so called from the presence in most cases of a backbone composed of numerous joints or Vertebrae, which constitutes the centre of the skeleton and at the same time supports and protects the central parts of the nervous system.

Whorls

The circles or spiral lines in which the parts of plants are arranged upon the axis of growth.

Workers

See neuters.

Zoea-Stage

The earliest stage in the development of many of the higher Crustacea, so called from the name of Zoea applied to these young animals when they were supposed to constitute a peculiar genus.

Zooids

In many of the lower animals (such as the Corals, Medusae, etc.) reproduction takes place in two ways, namely, by means of eggs and by a process of budding with or without separation from the parent of the product of the latter, which is often very different from that of the egg. The individuality of the species is represented by the whole of the form produced between two sexual reproductions; and these forms, which are apparently individual animals, have been called Zooide.

List of Illustrations

Diagram showing descent of varieties of species in a genus.

Endnotes

Aristotle, in his Physicae Auscultationes (lib.2, cap.8, s.2), after remarking that rain does not fall in order to make the corn grow, any more than it falls to spoil the farmer’s corn when threshed out of doors, applies the same argument to organisation; and adds (as translated by Mr. Clair Grece, who first pointed out the passage to me), “So what hinders the different parts (of the body) from having this merely accidental relation in nature? as the teeth, for example, grow by necessity, the front ones sharp, adapted for dividing, and the grinders flat, and serviceable for masticating the food; since they were not made for the sake of this, but it was the result of accident. And in like manner as to other parts in which there appears to exist an adaptation to an end. Wheresoever, therefore, all things together (that is all the parts of one whole) happened like as if they were made for the sake of something, these were preserved, having been appropriately constituted by an internal spontaneity; and whatsoever things were not thus constituted, perished and still perish.” We here see the principle of natural selection shadowed forth, but how little Aristotle fully comprehended the principle, is shown by his remarks on the formation of the teeth. ↩

I have taken the date of the first publication of Lamarck from Isidore Geoffroy Saint-Hilaire’s (Hist. Nat. Générale, tom. ii page 405, 1859) excellent history of opinion on this subject. In this work a full account is given of Buffon’s conclusions on the same subject. It is curious how largely my grandfather, Dr. Erasmus Darwin, anticipated the views and erroneous grounds of opinion of Lamarck in his “Zoonomia” (vol. i pages 500⁠–⁠510), published in 1794. According to Isid. Geoffroy there is no doubt that Goethe was an extreme partisan of similar views, as shown in the introduction to a work written in 1794 and 1795, but not published till long afterward; he has pointedly remarked (“Goethe als Naturforscher,” von Dr. Karl Meding, s. 34) that the future question for naturalists will be how, for instance, cattle got their horns and not for what they are used. It is rather a singular instance of the manner in which similar views arise at about the same time, that Goethe in Germany, Dr. Darwin in England, and Geoffroy Saint-Hilaire (as we shall immediately see) in France, came to the same conclusion on the origin of species, in the years 1794⁠–⁠5. ↩

From references in Bronn’s Untersuchungen uber die Entwickelungs-Gesetze, it appears that the celebrated botanist and palaeontologist Unger published, in 1852, his belief that species undergo development and modification. Dalton, likewise, in Pander and Dalton’s work on Fossil Sloths, expressed, in 1821, a similar belief. Similar views have, as is well known, been maintained by Oken in his mystical Natur-Philosophie. From other references in Godron’s work Sur l’Espece, it seems that Bory St. Vincent, Burdach, Poiret and Fries, have all admitted that new species are continually being produced. I may add, that of the thirty-four authors named in this Historical Sketch, who believe in the modification of species, or at least disbelieve in separate acts of creation, twenty-seven have written on special branches of natural history or geology.