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the Azores, a female rabbit with her young. They increased 

 enormously, but diminishing in size to half the weight of their 

 predecessors. In 1861 specimens were brought to the Zoological 

 Gardens, London, and though many attempts were made to cross 

 them with others, the attempts failed, indicating that in this case 

 the change had reached the limit of sterility. In the case of plants 

 he gives abundant instances of variation ; variation by seed, and 

 bud variation. The moss rose was produced from a common rose 

 by bud variation. New varieties of the gooseberry have been 

 formed in the same way. By bud variation the nectarine has been 

 produced from the peach. Cabbages, peas, beans, flowers of all 

 kinds, are constantly yielding new varieties ; the flowers of the 

 present day have reached a perfection totally unknown to our pre- 

 decessors. With- animals, strongly-marked varieties have occurred. 

 The short-legged Ancon sheep of Massachusetts — the Manchamp 

 merino breed of sheep — shown at the 1861 Exhibition, was obtained 

 from a ram descended from the ordinary sheep. The proceedings of 

 the Zoological Society for i860 report the appearance of a new va- 

 riety of the peacock, which appeared suddenly in a flock of the 

 common kinds belonging to Lord Brownlow. In some cases the new 

 variety has been preserved by human selection ; in other cases the 

 new breed has increased to the extinction of the others. To the 

 question, how, without human selection, new varieties can be pre- 

 served in nature, Mr. Darwin gives a most important answer. He 

 shows that there is such a thing as natural selection, more potent, 

 more effectual, than man's selection ; that can act on all points, at 

 all ages, on invisible as well as visible characters. It arises from 

 the struggle for existence, consequent on the fact that the repro- 

 ductive power of animals tends to act in a geometrical ratio. If 

 limited in area, in food, or through the attacks of other animals, 

 the weakest will perish ; the strongest survive. If the conditions 

 of life change, any slight variation which gives to an individual an 

 advantage in the struggle, will increase his chance of living and of 

 having progeny. The offspring that inherit the advantage will 

 survive, and thus the improvement will be gained by all the living 

 descendants ; the less improved perishing in a greater ratio than 



