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ly arisen in a seedling。 So it has probably been with the turnspit dog； and this is known to have been the case with the ancon sheep。 But when we compare the dray…horse and race…horse； the dromedary and camel； the various breeds of sheep fitted either for cultivated land or mountain pasture； with the wool of one breed good for one purpose； and that of another breed for another purpose； when we compare the many breeds of dogs； each good for man in very different ways； when we compare the gamecock； so pertinacious in battle； with other breeds so little quarrelsome； with 'everlasting layers' which never desire to sit； and with the bantam so small and elegant； when we compare the host of agricultural； culinary； orchard； and flower…garden races of plants； most useful to man at different seasons and for different purposes； or so beautiful in his eyes； we must； I think； look further than to mere variability。 We cannot suppose that all the breeds were suddenly produced as perfect and as useful as we now see them； indeed； in several cases； we know that this has not been their history。 The key is man's power of accumulative selection： nature gives successive variations； man adds them up in certain directions useful to him。 In this sense he may be said to make for himself useful breeds。
The great power of this principle of selection is not hypothetical。 It is certain that several of our eminent breeders have； even within a single lifetime； modified to a large extent some breeds of cattle and sheep。 In order fully to realise what they have done； it is almost necessary to read several of the many treatises devoted to this subject； and to inspect the animals。 Breeders habitually speak of an animal's organisation as something quite plastic； which they can model almost as they please。 If I had space I could quote numerous passages to this effect from highly competent authorities。 Youatt； who was probably better acquainted with the works of agriculturalists than almost any other individual； and who was himself a very good judge of an animal； speaks of the principle of selection as 'that which enables the agriculturist； not only to modify the character of his flock； but to change it altogether。 It is the magician's wand； by means of which he may summon into life whatever form and mould he pleases。' Lord Somerville； speaking of what breeders have done for sheep； says： 'It would seem as if they had chalked out upon a wall a form perfect in itself； and then had given it existence。' That most skilful breeder； Sir John Sebright； used to say； with respect to pigeons； that 'he would produce any given feather in three years； but it would take him six years to obtain head and beak。' In Saxony the importance of the principle of selection in regard to merino sheep is so fully recognised； that men follow it as a trade： the sheep are placed on a table and are studied； like a picture by a connoisseur； this is done three times at intervals of months； and the sheep are each time marked and classed； so that the very best may ultimately be selected for breeding。
What English breeders have actually effected is proved by the enormous prices given for animals with a good pedigree； and these have now been exported to almost every quarter of the world。 The improvement is by no means generally due to crossing different breeds； all the best breeders are strongly opposed to this practice； except sometimes amongst closely allied sub…breeds。 And when a cross has been made； the closest selection is far more indispensable even than in ordinary cases。 If selection consisted merely in separating some very distinct variety； and breeding from it； the principle would be so obvious as hardly to be worth notice； but its importance consists in the great effect produced by the accumulation in one direction； during successive generations； of differences absolutely inappreciable by an uneducated eye differences which I for one have vainly attempted to appreciate。 Not one man in a thousand has accuracy of eye and judgement sufficient to become an eminent breeder。 If gifted with these qualities； and he studies his subject for years； and devotes his lifetime to it with indomitable perseverance； he will succeed； and may make great improvements； if he wants any of these qualities； he will assuredly fail。 Few would readily believe in the natural capacity and years of practice requisite to become even a skilful pigeon…fancier。
The same principles are followed by horticulturists； but the variations are here often more abrupt。 No one supposes that our choicest productions have been produced by a single variation from the aboriginal stock。 We have proofs that this is not so in some cases； in which exact records have been kept； thus； to give a very trifling instance； the steadily…increasing size of the common gooseberry may be quoted。 We see an astonishing improvement in many florists' flowers； when the flowers of the present day are compared with drawings made only twenty or thirty years ago。 When a race of plants is once pretty well established； the seed…raisers do not pick out the best plants； but merely go over their seed…beds； and pull up the 'rogues；' as they call the plants that deviate from the proper standard。 With animals this kind of selection is； in fact； also followed； for hardly any one is so careless as to allow his worst animals to breed。
In regard to plants； there is another means of observing the accumulated effects of selection namely； by comparing the diversity of flowers in the different varieties of the same species in the flower…garden； the diversity of leaves； pods； or tubers； or whatever part is valued； in the kitchen…garden； in comparison with the flowers of the same varieties； and the diversity of fruit of the same species in the orchard； in comparison with the leaves and flowers of the same set of varieties。 See how different the leaves of the cabbage are； and how extremely alike the flowers； how unlike the flowers of the heartsease are； and how alike the leaves； how much the fruit of the different kinds of gooseberries differ in size； colour； shape； and hairiness； and yet the flowers present very slight differences。 It is not that the varieties which differ largely in some one point do not differ at all in other points； this is hardly ever； perhaps never； the case。 The laws of correlation of growth； the importance of which should never be overlooked； will ensure some differences； but； as a general rule； I cannot doubt that the continued selection of slight variations； either in the leaves； the flowers； or the fruit； will produce races differing from each other chiefly in these characters。
It may be objected that the principle of selection has been reduced to methodical practice for scarcely more than three…quarters of a century； it has certainly been more attended to of late years； and many treatises have been published on the subject； and the result； I may add； has been； in a corresponding degree； rapid and important。 But it is very far from true that the principle is a modern discovery。 I could give several references to the full acknowledgement of the importance of the principle in works of high antiquity。 In rude and barbarous periods of English history cho