its mean- 



NATURAL SELECTION 117 



of cleverness and courage. The differences between one fish 

 and another in this respect must be much less marked, but, 

 granting that they exist in a considerable degree, yet, the off- 

 spring being left untended, the superiority of a particular parent 

 will not help its brood to survive except in so far as they inherit 

 the superiority. With mammals and birds the offspring of the 

 more vigorous and better endowed have a double advantage : 

 first, they probably inherit their parents' qualities of mind and 

 body ; secondly, they receive from their parents a better start in 

 life. 



During this early period the young mammal, sheltered from play and 

 the world and its cruel realities, is not merely eating and grow- ! ts r 

 ing. He is devoted to play, and in his play exercises all his 

 muscles and his faculties. If growth were all that is re- 

 quired, a recurrence of hearty meals at short intervals and 

 no exercise beyond that of eating would be the best thing. But 

 during this period of inactivity much more than mere growth has 

 to take place. The various muscles have to be coadapted, and 

 their activities co-ordinated. Even a steam-engine, that is meant 

 to go through one set programme and no more, often sticks and 

 jars, and is restive till the various parts have learnt to work in 

 harmony together. 2 propos of this, we may recall the cater- 

 pillar and his great feat of spinning a cocoon. It is a truly 

 wonderful performance. But there is the beginning and end of 

 his skill. He has no versatility. A lamb, on the other hand, 

 which is not usually counted among the cleverest of animals, has 

 to perfect all his paces, to make an art of his skipping, his high- 

 jumping and broad-jumping. For I am imagining him a member 

 of a wild stock with enemies that he will have to outstrip. 

 Besides this, he must learn what is good to eat and what is 

 not ; among his neighbours on the mountain slopes, who are 

 dangerous and who are harmless. The requisite knowledge of 

 the last-mentioned subjects he will get by watching his mother 

 and the rest of the flock, and imitating them. But much that is 

 important to him he will learn by play, the importance of which 

 has been made clear to the world by Karl Groos in his Play 

 of Animals. Puppies, kittens, young lions, tigers, leopards, 



