416 CONCLUDING KEMARKS. Chap. XXVIII. 



animals and plants has been greatly exaggerated, though 

 doubt to a certain extent it fixista. 



b ~ no 



to a certain extent it exists. It would be opposed to all 

 e principles inculcated in this work, if domestic animals, when 

 posed to new conditions and compelled to struggle for their 



s 



host of foreio 



were not in 



the course of time in some manner modified. It should also 

 be remembered that many characters lie latent in all organic 

 beings ready to be evolved under fitting conditions ; and in breeds 

 modified within recent times the tendency to reversion is parti- 

 cularly strong. But the antiquity of various breeds clearly proves 

 that they remain nearly constant as long as their conditions of 

 life remain the same. 



It has been boldly maintained by some authors that the 

 amount of variation to which our domestic productions are liable 

 is strictly limited; but this is an assertion resting on little 

 evidence. Whether or not the amount in any particular direc- 

 tion is fixed, the tendency to general variability seems unlimited. 

 Cattle, sheep, and pigs have been domesticated and have varied 

 from the remotest period, as shown by the researches of Eiiti- 

 meyer and others, yet these animals have, within quite recent 

 times, been improved in an unparalleled degree ; and this im- 



ies continued variability of structure. Wheat, as we know 



9 



from the remains found in the Swiss lake-habitations, is one of 

 the most anciently cultivated plants, yet at the present day new 

 and better varieties occasionally arise. It may be that an ox 

 will never be produced of larger size or finer proportions than 

 our present animals, or a race-horse fleeter than Eclipse, or a 

 gooseberry larger than the London variety; but he would be 

 a bold man who would assert that the extreme limit in these 

 respects has been finally attained. With flowers and fruit it 

 has repeatedly been asserted that perfection has been reached, 

 but the standard has soon been excelled. A breed of pigeons 

 may never be produced with a beak shorter than that of the 

 present short-faced tumbler, or with one longer than that of the 

 English carrier, for these birds have weak constitutions and are 

 bad breeders ; but the shortness and length of the beak are the 

 points which have been steadily improved during at least the 

 last 150 years ; and some of the best judges deny that the goal has 

 yet been reached. We may, also, reasonably suspect, from what 



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