Charles Darwin - The Foundations of the Origin of Species

Therefore if in any country or district all animals of one species be allowed freely to cross, any small tendency in them to vary will be constantly counteracted. Secondly reversion to parent form – analogue of vis medicatrix 44 44 There is an article on the vis medicatrix in Brougham’s Dissertations , 1839, a copy of which is in the author’s library. . But if man selects, then new races rapidly formed, – of late years systematically followed, – in most ancient times often practically followed 45 45 This is the classification of selection into methodical and unconscious given in the Origin , Ed. i. p. 33, vi. p. 38. . By such selection make race-horse, dray-horse – one cow good for tallow, another for eating &c. – one plant's good lay «illegible» in leaves another in fruit &c. &c.: the same plant to supply his wants at different times of year. By former means animals become adapted, as a direct effect to a cause, to external conditions, as size of body to amount of food. By this latter means they may also be so adapted, but further they may be adapted to ends and pursuits, which by no possibility can affect growth, as existence of tallow-chandler cannot tend to make fat. In such selected races, if not removed to new conditions, and «if» preserved from all cross, after several generations become very true, like each other and not varying. But man 46 46 This passage, and a similar discussion on the power of the Creator (p. 6), correspond to the comparison between the selective capacities of man and nature, in the Origin , Ed. i. p. 83, vi. p. 102. selects only «?» what is useful and curious – has bad judgment, is capricious, – grudges to destroy those that do not come up to his pattern, – has no [knowledge] power of selecting according to internal variations, – can hardly keep his conditions uniform, – [cannot] does not select those best adapted to the conditions under which «the» form «?» lives, but those most useful to him. This might all be otherwise.

Let us see how far above principles of variation apply to wild animals. Wild animals vary exceedingly little – yet they are known as individuals 47 47 i. e. they are individually distinguishable. . British Plants, in many genera number quite uncertain of varieties and species: in shells chiefly external conditions 48 48 See Origin , Ed. i. p. 133, vi. p. 165. . Primrose and cowslip. Wild animals from different [countries can be recognized]. Specific character gives some organs as varying. Variations analogous in kind, but less in degree with domesticated animals – chiefly external and less important parts.

Our experience would lead us to expect that any and every one of these organisms would vary if «the organism were» taken away «?» and placed under new conditions. Geology proclaims a constant round of change, bringing into play, by every possible «?» change of climate and the death of pre-existing inhabitants, endless variations of new conditions. These «?» generally very slow, doubtful though «illegible» how far the slowness «?» would produce tendency to vary. But Geolog«ists» show change in configuration which, together with the accidents of air and water and the means of transportal which every being possesses, must occasionally bring, rather suddenly, organism to new conditions and «?» expose it for several generations. Hence «?» we should expect every now and then a wild form to vary 49 49 When the author wrote this sketch he seems not to have been so fully convinced of the general occurrence of variation in nature as he afterwards became. The above passage in the text possibly suggests that at this time he laid more stress on sports or mutations than was afterwards the case. ; possibly this may be cause of some species varying more than others.

According to nature of new conditions, so we might expect all or majority of organisms born under them to vary in some definite way. Further we might expect that the mould in which they are cast would likewise vary in some small degree. But is there any means of selecting those offspring which vary in the same manner, crossing them and keeping their offspring separate and thus producing selected races: otherwise as the wild animals freely cross, so must such small heterogeneous varieties be constantly counter-balanced and lost, and a uniformity of character [kept up] preserved. The former variation as the direct and necessary effects of causes, which we can see can act on them, as size of body from amount of food, effect of certain kinds of food on certain parts of bodies &c. &c.; such new varieties may then become adapted to those external [natural] agencies which act on them. But can varieties be produced adapted to end, which cannot possibly influence their structure and which it is absurd to look «at» as effects of chance. Can varieties like some vars of domesticated animals, like almost all wild species be produced adapted by exquisite means to prey on one animal or to escape from another, – or rather, as it puts out of question effects of intelligence and habits, can a plant become adapted to animals, as a plant which cannot be impregnated without agency of insect; or hooked seeds depending on animal“s existence: woolly animals cannot have any direct effect on seeds of plant. This point which all theories about climate adapting woodpecker 50 50 The author may possibly have taken the case of the woodpecker from Buffon, Histoire Nat. des Oiseaux , T. vii. p. 3, 1780, where however it is treated from a different point of view. He uses it more than once, see for instance Origin , Ed. i. pp. 3, 60, 184, vi. pp. 3, 76, 220. The passage in the text corresponds with a discussion on the woodpecker and the mistletoe in Origin , Ed. i. p. 3, vi. p. 3. to crawl «?» up trees, «illegible» miseltoe, «sentence incomplete». But if every part of a plant or animal was to vary «illegible», and if a being infinitely more sagacious than man (not an omniscient creator) during thousands and thousands of years were to select all the variations which tended towards certain ends ([or were to produce causes «?» which tended to the same end]), for instance, if he foresaw a canine animal would be better off, owing to the country producing more hares, if he were longer legged and keener sight, – greyhound produced 51 51 This illustration occurs in the Origin , Ed. i. pp. 90, 91, vi. pp. 110, 111. . If he saw that aquatic «animal would need» skinned toes. If for some unknown cause he found it would advantage a plant, which «?» like most plants is occasionally visited by bees &c.: if that plant’s seed were occasionally eaten by birds and were then carried on to rotten trees, he might select trees with fruit more agreeable to such birds as perched, to ensure their being carried to trees; if he perceived those birds more often dropped the seeds, he might well have selected a bird who would «illegible» rotten trees or [gradually select plants which «he» had proved to live on less and less rotten trees]. Who, seeing how plants vary in garden, what blind foolish man has done 52 52 See Origin , Ed. i. p. 83, vi. p. 102, where the word Creator is replaced by Nature . in a few years, will deny an all-seeing being in thousands of years could effect (if the Creator chose to do so), either by his own direct foresight or by intermediate means, – which will represent «?» the creator of this universe. Seems usual means. Be it remembered I have nothing to say about life and mind and all forms descending from one common type 53 53 Note in the original. “Good place to introduce, saying reasons hereafter to be given, how far I extend theory, say to all mammalia – reasons growing weaker and weaker.” . I speak of the variation of the existing great divisions of the organised kingdom, how far I would go, hereafter to be seen.