The foundations of The origin of species : a sketch written in 1842 / edited by Francis Darwin.
- Charles Darwin
- Date:
- 1909
Licence: Public Domain Mark
Credit: The foundations of The origin of species : a sketch written in 1842 / edited by Francis Darwin. Source: Wellcome Collection.
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![be contaminated with a cross of another race, and agriculturists know how difficult they find always to prevent this,—effect would be trueness. This char¬ acter and sterility when crossed, and generally a greater amount of difference, are two main features, which distinguish domestic races from species. [Sterility not universal admitted by all1. Gladiolus, Crinum, Calceolaria2 must be species if there be such a thing. Races of dogs and oxen: but certainly very general; indeed a gradation of sterility most perfect3 very general. Some nearest species will not cross (crocus, some heath (?)), some genera cross readily (fowls4 and grouse, peacock &c.). Hybrids no ways monstrous quite perfect except secretions5 6 hence even the mule has bred,—character of sterility, especially a few years ago (?) thought very much more universal than it now is, has been thought the distinguishing character; indeed it is obvious if all forms freely crossed, nature would be a chaos. But the very gradation of the character, even if it always existed in some degree which it does not, renders it impossible as marks (?) those (?) suppose distinct as species0]. Will analogy throw any light 1 The meaning is “That sterility is not universal is admitted by all.” 2 See Var. under Dom., Ed. 2, i. p. 388, where the garden forms of Gladiolus and Calceolaria are said to be derived from crosses between distinct species. Herbert’s hybrid Crinums are discussed in the Origin, Ed. i. p. 250, vi. p. 370. It is well known that the author believed in a multiple origin of domestic dogs. 3 The argument from gradation in sterility is given in the Origin, Ed. i. pp. 248, 255, vi. pp. 368, 375. In the Origin, I have not come across the cases mentioned, viz. crocus, heath, or grouse and fowl or peacock. For sterility between closely allied species, see Origin, Ed. i. p. 257, vi. p. 377. In the present essay the author does not distinguish between fertility between species and the fertility of the hybrid offspring, a point on which he insists in the Origin, Ed. i. p. 245, vi. p. 365. 4 Ackermann (Ber. d. Vereins f. Naturkunde zu Kassel, 1898, p. 23) quotes from Gloger that a cross has been effected between a domestic hen and a Tetrao tetrix; the offspring died when three days old. 6 No doubt the sexual cells are meant. I do not know on what evidence it is stated that the mule has bred. 6 The sentence is all but illegible. I think that the author refers to forms usually ranked as varieties having been marked as species when it was](https://iiif.wellcomecollection.org/image/b31351761_0045.jp2/full/800%2C/0/default.jpg)
