66 



THE YOUNG 



NATUEALIST. 



tance. This animal, though not possess- 

 ing speed or power of endurance in 

 excess, yet escaped destruction by reason 

 of its colour helping to conceal it from 

 its pursuers. It would he likely to 

 transmit this quality to its progeny in 

 some degree, and those which were best 

 adapted for concealment, or most 

 difficult to observe would escape the 

 destruction that would come upon 

 those differently coloured or marked. 

 Again, let this process go on for many 

 successive generations, each one preserv- 

 ing in some degree the characters that 

 were advantageous. At the end of the 

 time what will be the result ? On the 

 one hand we would have animals that had 

 been " selected," over a long period, for 

 speed and powers of endurance. On the 

 other we would have animals that had 

 been *' selected for colour ; speed or 

 power of endurance not being a factor 

 at all. We know what man can do in 

 a very few generations from careful 

 selection, and it is only fair to assume 

 that Nature can select equally well, and 

 with equal results. It must, however, 

 be borne in mind that Nature never 

 moves by jumps, and that the natural 

 process is necessarily a much slower 

 one, than under domestication. A 

 stock breeder pairs his animals to pro- 

 duce certain results, which he calculates 

 on before hand. He selects those whose 

 qualities are nearest to what he desires 

 to obtain. Hence, in a comparatively 

 short time he accomplishes his object, 

 Nature necessarily moves more slowly. 

 The animal, whose colour is better 

 adapted for concealment, is unconscious 



of its advantage, and probably pairs 

 with the ordinary form. The change, 

 therefore, is but slight, and would soon 

 be lost, but that a similar variety may 

 occur and bring the change back again. 

 If it be an advantage, it will at beet 

 have a tendency to be preserved and 

 perpetuated. If a variety be a dis- 

 advantage, it is certain to disappear 

 very speedily. Enormously long periods 

 of time are needed to produce great 

 change, but if these periods be admitted 

 the rest follows almost as a matter of 

 course. We thus see how two specie? 

 might, in course of time, spring fron 

 one. The one would be noted for speec 

 and power of endurance ; the other fo; 

 being coloured or marked so like th( 

 surrounding country as to escape detec 

 tion. One would change in its organs 

 of locomotion, and would probabl) 

 become slighter in make and longer in 

 leg. The other would need neither of 

 these changes, and from its better con- 

 cealment would need to move less, 

 would become more bulky and less 

 nimble. 



In our next paper we will speak of 

 animals under domestication, reverting to 

 their original form when set at liberty. 



TO CORRESPONDENTS. 



All communications to be sent to J. E. Kobson, 15 

 Northgate, Hartlepool; or to S. L. Mosley Beau- 

 mont Park, Huddersfield. 



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