174 BOMBAY DUCKS 



the legs of one antelope are half an inch longer than 

 those of another, the former has certainly, other things 

 being equal, an advantage in the struggle for existence. 

 But other things are so rarely equal. A slight advan- 

 tage, such as this, may be easily counterbalanced by 

 luck. 



Two antelopes may be feeding together, when they 

 are seen by a beast of prey. They fly together, and 

 the faster one soon begins to lead, but he happens to 

 stumble into a quagmire ; his neighbour profits by his 

 mistake and takes another course, so that the poor 

 creature who is floundering in the soft mud is fallen 

 upon and devoured by the pursuer, while its less speedy 

 companion escapes. 



On the other hand, it is easy to see how a little extra 

 brain-power can assist a species. A cute antelope may 

 not be particularly fleet, nor very strong, but he will be 

 careful to choose as feeding grounds places where he 

 cannot be surprised, and, when he is chased, he will 

 follow the course best adapted to his mode of pro- 

 gression ; carefully avoiding all soft ground, he will profit 

 to the uttermost by his knowledge of the locality ; he 

 will run, as far as possible, in a straight line, so that his 

 pursuer will not be able to cut off corners. 



Hundreds of athletic species, which are known to us 

 only as fossils, might to-day be living, if, when the 

 struggle for existence began to press hardly upon them, 

 they had had the wit to build boats and sail away to 

 some corner of the earth where the competition was a 

 little less keen. Every organ of every animal is subject 

 to variation, and the brain forms no exception. 



