386 AIM AND PKOGRESS OF PHYSICAL SCIENCE. 



in common, the majority of their offspring also possess 

 them ; and if among the offspring there are some which 

 present these peculiarities in a less marked degree, there 

 will, on the other hand, always be found among a great 

 number, others in which the same peculiarities have 

 become intensified. If, now, these be selected to propa- 

 gate offspring, a greater and greater intensification of 

 these peculiarities may be attained and transmitted. 

 This is, in fact, the method employed in cattle-breeding 

 and gardening, in order with greater certainty to obtain 

 new breeds and varieties, with well-marked different 

 characters. The experience of artificial breeding is to 

 be regarded, from a scientific point of view, as an ex- 

 perimental confirmation of the law under discussion ; 

 and, in fact, this experiment has proved successful, and 

 is still doing so, with species of every class of the animal 

 kingdom, and, with respect to the most different organs 

 of the body, in a vast number of instances. 



After the general application of the law of trans- 

 mission had been established in this way, it only re- 

 mained for Darwin to discuss the bearings of the question 

 as regards animals and plants in the wild state. The 

 result which has been arrived at is that those individuals 

 whicli are distinguished in the struggle for existence 

 by some advantageous quality, are the most likely to 

 produce offspring, and thus transmit to them their ad- 

 vantageous qualities. And in this way from generation 

 to generation a gradual adjustment is arrived at in the 

 adaptation of each species of living creation to the 

 conditions under which it has to live until the type 

 has reached such a degree of perfection that any sub- 

 stantial variation from it is a disadvantage. It will 

 then remain unchanged so long as the external con- 

 ditions of its existence remain materially unaltered. 

 Such an almost absolutely fixed condition appears to 



